Germany isn't that different to US (I think, I'm in Aus but I've been there and it's same as Aus anyway)
Could you find out more about the people your visiting and maybe get them something to do with their interests? eg. If they're big on farming get them something farm-related? Don't know what it would be though.
Or get them something considered really 'American.' For me, little cans of Vegemite would be the obvious choice but you don't have that so whatever's considered 'American' try bringing some of that.
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