American food is so much different. I'd say raid the grocery store's candy aisle. Our sodas are different too, but that's pricey to mail since it's so heavy.
Old Navy might still have some of their 4th of July shirts for $5.
James Avery jewelry is very American. I think they may be in Texas only.
I lived in England when I was in Middle School. I was a big candy-goer, so that's why I said that. Some friends came to visit us from England just last week and brought us our favorite british candies and it was such a treat! Granted, you have to know what is 'different.' One package of candy they gave us was the same thing we have here (M&Ms, Milky Way) and one package was different (Flake bars, Aero bars). So in England they have Mars brand and Cadbury brand. They may or may not have Hershey's and Neslte's. Who KNOWS what they have in Czech Republic.
Is there not a way to just call her and casually start a conversation about what she misses about America?