I’m hoping to reunite with some distant British relatives this summer - adults (some my age, some in their 30s-40s), a couple of preteens/teens, I think a preschooler, and a baby. Except for the older folks, I’ve never met them and know nothing about their interests. Would like to bring small “American” gifts. Not food (someone suggested maple syrup), definitely not MAGA hats. 
I have to travel light due to itinerary.
I’m stumped. Please help!
Fischer Price toy for the toddler/preschooler.
Baseball hats
A baseball
When my DD left the Peace Corps, she wanted something American to give to a lot of her friends there. We found calendars that had pics of famous American sites…Grand Canyon, Old Faithful, Mt. Rushmore, Statue of Liberty, etc. They were inexpensive and easy to transport.
I know they aren’t “American”but I think I would get Duplo Blocks for the little babes. Just a small set.
Consider some classic American books for young children. By American authors, perhaps about our country.
Yankees BB caps and t-shirts
Yuck to a specific baseball team unless you are from there. Why not Packers’ stuff? Onslo on the British show “Keeping Up Appearances” wore a WI related cap, btw.
You can’t encompass the whole US so why not go with something from your region?
note cards, coasters, playing cards featuring American Artists (Frank Lloyd Wright items even include little building sets)
I second the suggestion of books for the kids. Amelia Bedelia, Misty of Chincoteague, Little House series, Pat the Bunny—all big hits with my English relatives. Actually, my mother-in-law enjoys American books, too, especially a mystery series set in Philadelphia and some recent novels set in New York City.
I’ve also had a good response from giving folks tea towels or fridge magnets from local sites. And I know you said no food, but apple butter is always a big hit!
If your relatives celebrate Christmas, how about Christmas tree ornaments that reflect something American or something that relates to your life or part of the country?
I have a few ornaments that didn’t make a huge impact when I received them, but I think about the givers every year when I pull them out to put them on the tree. Sadly, many other token gifts seem to go unused or end up in the trash.
If it’s a glass ornament, you’d need to pack carefully. But it would be light!
If it’s not glass and has a back-side, you could use a special pen to note the occasion. One of mine reads, “Zip Family Reunion, 1993.”
Cowboy hat, Statue of Liberty, pizza, baseball/bat, Golden Gate Bridge, burger, football, alligator, bee hive, car, tennis racquet, pickle, whatever!
This time of year may be challenging, but ebay and Amazon could be your friends.
I would go with some local stuff from your state.
I would get something from the MOMA store. It has the neatest toys and American stuff for adults - all the derivatives of Warhol, etc.
Also, cloth shopping/tote bags printed with something local or obviously American.
For children, an MLS soccer ball (it can be deflated for travel).
I think I’d check whether the children’s toys and books are commonly available there. (Fisher Price is.) And what would we really expect them to do with, lol, sports memorabilia? (I can’t imagine my former German hosts wanting a baseball cap, sorry.) To my thinking, it’s not like they came here and chose. And British culture isn’t that different then ours (not like that trip to Africa.) Some of the very place-specific items might just be “very American,” but white elephants.
That said, maybe a small local specialties cookbook.
My kiddo did take maple syrup to France and they liked it.
Danforth pewter. Charleston area sweetgrass baskets.
I don’t know which part of America you’re in, but I’m from an area known for ranching, and my European and Asian friends are for some reason fascinated by cowboy paraphernalia.
I think OP doesn’t know most of these folks and what they’d be interested in.
Oops, posted twice somehow.
I agree that something local from your state might be a good idea. When I lived in MN, I’d take a small bag of wild rice sometimes as a gift.