Also there are always basketball/frisbee/soccer pick up games going on- maybe a bag of varied sports stuff
A mini fridge if he or a roommate doesn’t already have one. UCSD allows up to 5 cf. and I would suggest that size as most likely he will be in a triple and sharing it with 2 others. There is really no room for microwaves or coffee pots but they are available in the dorms.
How about UCSD sweatshirt??
Also UCSD offers some summer trips designed to ease new students in socially- my S didn’t do any so I don’t know anything first hand but I think there was river rafting, hiking, camping etc.
My DD doesn’t like ‘stuff’ so we plan to give her a lifetime membership in her music society for her high school graduation.
What about an Amazon gift card? You can buy almost everything at Amazon including textbooks.
Also totally “OK” to not give your own child a graduation gift. We are not a family that feels the need to “gift” every occasion - well, unless you consider going out for ice cream a gift. 
Such great ideas. @takeitallin Do most students drag their current bike down to campus or buy something local? It would be a long drive with the bike hanging off the back of the mini-van. Never feel totally safe with that.
@himom That gives me an idea - a framed picture of our dog.
If you want something low-cost, but unobtainable, see if you can secure a SIO (Scripps Institute of Oceanography) parking decal for his 2-series BMW convertible. That way he can park down by the beach. Need some inside connection for that (plus the aforementioned convertible)!
She already has a Keurig, but we got her a mini blender and a Starbucks giftcard. She also got a tablet.
@patertrium our S took an old bike we already had his first year. To tell you the truth , I think he only rode it a couple of times. He did not take it again this year. He uses a skateboard to get around campus as he says it is easier than a bike. Of course you could always buy one there.
Yes, around campus, many kids use either a skateboard or bike. Our kids bought $7 beater bikes which barely got the to camps and back, but were never stolen.
Another idea I had was a jar full of quarters for the laundromat. Maybe even include it in a gift basket with detergent, spot remover and fabric softener.
Check the laundry facilities first. Many no longer use quarters. They use campus points card or credit card.
How about some gift cards to local pizza places that deliver!
We gave money for a Hawaii trip to go by themselves with some of her elementary/middle school friends. I also paid for the camping trip to Sierra from UCSD, I was hopping she started knowing somebody. She is keeping in touch with one guy regularly. I thought it was a fun trip but it turned out it was more meaningful as part of growing up, one of the thing I remember was to sleep in a tent by herself within distance from the others so she had time to think through things. She was cold and came out of the trip less worried about bugs.
She bought her own bike but only used it the first year. She rarely used it the second year and she will have a car by the third year because she will be living off campus. Mini fridge was part of moving cost so it was not considered gift.
fridge, laptop, duvet, good towels, sweatshirt from the college, bulletin board, …if it is a guy then a watch.
Rules vary a lot about appliances including fridges, microwaves and others, especially in dorms. Check first. Some ban completely, some provide them. There’s no sense in buying something banned or provided.
My son never wears a watch…so YMMV on that gift too. He uses his phone to check the time.
Our DD got a new laptop for HS graduation.
Our DS got a very expensive instrument case…about the same price as a computer.
If we are talking practical gifts… A good mattress pad is worth the $$ invested. Dorm mattresses are notoriously hard and lumpy!
Nice laptop was definitely a gift. Mine got something from Apple.