Many years ago we took D to her new school and there was not a fan left in the city.
You can order one from BBB and pick it up in the school’s city if you are not driving.
In my experience, for the guy who is happy to sleep on the floor (I have been married to one for 34 years) he/she would prefer not to have anything extra under him than he needs. He has hated any mattress topper, including just a pad, that I have tried to put on his bed. I would not buy him anything for the bed unless you want it in the dumpster (as happened with my daughter). My son liked his. If you do get something, I am a fan of the simple egg crate.
No one in our house sleeps on a mattress topper. So the thought to take one to college would never occur to us. To me, keep dorm room as simple as possible. Especially with guys (at least vast majority of them). What I tell parents I know (and in reality its moms who tend to do this) who go crazy with buying dorm stuff (mattress toppers, comforters, dust ruffles, etc. is take picture of the dorm once you have it all set up and know it will never ever look that way again. Also I suggest that you meet your kid in the lobby going forward. As the year moves on, there is a good chance you won’t wont to see your kids’ room.
The need for a mattress topper will depend on how bad the mattresses are in the dorm. My D definitely needed one in boarding school as the mattresses were rocks. She just got used to the extra level of comfort so took it to college. The mattresses in her college dorm were not much better – super thin and hard.
They are expensive and bulky to handle when packing and storing, but D will be a junior next year and she still has the same one from boarding school. Invest in a good one and it will last. Just change the cover when needed.
Definitely buy a mattress pad. Your son won’t be used to the thin plastic mattresses used in dorms. But don’t get one any thicker than 3". They are very hard to store as it is. And I second the “no egg crate” suggestion. We had to buy a new one for my son’s soph year because his first one fell apart during storage over the summer. If you pay $100 for a 2-3 inch memory foam, it should last him all 4 years.
But you probably don’t sleep on a hard as a rock mattress bought in bulk for about $30 each. My kids had mattress toppers at home because I had one and they liked it, plus I knew they could take them to college. ALL their friends loved them and we should get a commission from Sealy for starting the trend.
My daughter could also sleep anywhere. I often found Legos and other toys in her bed and she never seemed to notice the discomfort. Now she won’t sleep without a foam pad. She just got a new mattress and pulled out her school pad for the summer.
S took an egg crate one and it was fine. D took a slightly nicer memory foam one but still only an inch thick, and it was fine. I can’t imagine trying to pack a 2-3" one, she has one on her bed and it is super bulky.
"No one in our house sleeps on a mattress topper. So the thought to take one to college would never occur to us. "
Remember that most dorm mattress are plastic coating enmeshed, cheap things. I would not want to sleep with only a sheet between me and one of those mattresses. In order to maximize on’e effectiveness as a student, having a cozy, comfy place to get a good night’s sleep is imperative, IMO. Money well spent. And it’s nothing frou frou looking - you don’t even see it.
@twoinanddone My son will be a junior in college this fall. He slept without a mattress topper for 2 years in the dorms. No problems. May well depend on what you are used to and the mattresses at any given college. My point is just any time I hear someone say a mattress topper is a must for college, I don’t think that is necessarily true.
Sometimes you don’t know you’re missing a great thing until you try it. 
We have bought this mattress pad multiple times (4 college kids) and it was great. Made a huge difference in comfort. Held up and could be used multiple years. Put on bed immediately, no smell - ready to go. Just don’t unpack it until you get there!
https://www.amazon.com/gp/product/B002NEG15E/ref=oh_aui_search_detailpage?ie=UTF8&psc=1
Thanks for the reminder, I just ordered another for #4.
^^^ @CADREAMIN , that’s the one my daughter used all four years (well, minus the year it was in storage because she went abroad). Her younger brother is now using it at the summer camp where he is working. It’s not as nice as the 3 inch pad he uses at college, but that thing is so bulky he had to pay extra to have it stored over the summer.
@Massmomm Great minds think alike! I believe the first ones I bought got passed on to somebody else like yours did - not sure they ever wear out. That’s funny too cause we first bought the 3" version (they were called Sleep Studio then) but that was almost too much padding for mine, and agree, it is certainly rough to move back home or to storage once it has been used. Even the two inch is pretty darn big when you are trying to fold/roll it up for transport. But what a difference it makes on ol’ springy dorm beds.
Of course it isn’t necessary. People graduated from college for centuries without them. They also graduated without cell phones and computers and LLBean raincoats, but those sure are nice modern conveniences.
Many years ago when I first became a working person with a small bit of disposable income, I bought nice sheets. Really nice sheets. All my disposable income for a month sheets. I loved them. I swore I’d never sleep on cheap sheets again. I figured I spend about 1/3 of my life in bed, so why not have the best?
@twoinanddone, I agree that it isn’t necessary to have a mattress pad, but it isn’t necessary to go to college either. If you do go, why not have a nice place to sleep? 
Although I have to say that the plastic coated mattresses my kids got were much worse than the thicker, possibly moldy mattresses I had back when the Romans still had an empire.
My kids had ok mattresses. And conventional mattress pads (a little quilted fabric.)
Did OP ask her son what he wants?
Kid one had a thin mattress that sort of was like a bunk house. We got him an egg crate foam topper…and a nice mattress pad. Made the bed comfy. We tossed the egg crate,at the end of every school year (it cost $10 or so…and really…one year was about all it could take). Washed the mattress pad with bleach…at home.
Second kid had a brand spanking new mattress on her dorm bed…that was well padded, and comfortable. We had ordered (BBB for pick up) a topper but cancelled that purchase, and instead got a good mattress pad. Well worth it.
In both cases, the XL twin mattresses were X thin, and also not as wide as a standard twin. We found that those jersey knit sheets regular twin size fit perfectly for both kids.
@lookingforward - he’s not too picky. I’m sure we could send him with just sheets and if he decides he needed more he would go to the store and get himself one. I really appreciate all the advice from everyone! Just trying to figure out what we actually need to get this summer to send with him. I’m beginning to think not much. He has a hand me down sheet/comforter set from a relative, another friend said she has her son’s egg crate (although I think I’ll check out the ones suggested), doesn’t sound like he needs a shower caddy :). He’s not moving so far away that he can’t come home and grab something over a weekend if needed. I’m thinking with the exception of maybe a set of XL jersey sheets because he likes them and they may be hard to find later to just let him move in and let us know if there is something he needs. We don’t have a lot of extra $$ to spend right now anyhow so it works well. Boys moving into dorms are much different than girls moving into dorms. Ha!
I slept in a freshman dorm when I was back on campus for my reunion last month. Pretty sure it was the same mattress I slept on in 1978. If I had the funds to make a donation restricted to new mattresses for all the dorms, I would.
DS’ college actually has the mattress pad on its “what to bring” list. (The mattresses are encased in plastic and very hard. I suspect that they are there solely to hold sheets as a piece of linoleum would have met several of the other standards of the mattress.) Certainly, he’d have survived without it, but in my mind, he had very little space that was exclusively his in that teeny tiny dorm room, so I felt there was some benefit , even beyond the physical, in having a very comfortable 21 square feet that was all his. And in full disclosure, he had very nice sheets and pillows as well. It made it easier for ME to drop him off knowing that his bed was, in his words, “super comfy”.
Of course it’s not mandatory, but a good night’s sleep can really set you up for a better day. Why not?