What might I send a homesick friend who's gone on a long trip? Bits of home that could be disposed of, but almost as easily packed up, along for the ride.
There's nothing like American humor. MAD was an early purveyor of knowing, slightly juvenile, culturally-aware laugh lines. (More recently, The Onion would work too.)
Assuming my friend has a digital device that goes to the ear, you can always use an extra pair.
"Best American Essays"
Any volume of this will trigger US appreciation for the million untold stories from here.
Larabar is a favorite, or maybe a Clif. Fruit rollups too. Portable and familiar snacks.
Tiny framed photo
A little art is a big comfort. I'd pick a favorite of that friend (celebrity, landscape, abstract).