Oh, but "you" did invent them, that's the point!
Original post has been flagged for a swipe at American tourists, but its list of "foreign" foods that are actually American is a good one. That list:
- pizza pepperoni (Italy)
- mayonaise (Belgium/France)
- paella (Spain)
This phenomenon is not unique to America though. Like, try Chindian food some time. Not invented in China.