Any sort of local dish your city/area is known for, such as New England Clam Chowder if you're in the northeastern part of the US, or Chili Spaghetti if you're in Cincinnati.
* Japanese Hibachi (yes, it's American!)
* Clam bake / Shrimp boil
* Americanized Chinese food (e.g. Panda Express.)
* Pizza (regular, NY style, Deep Dish style)
* BBQ (various styles)
* Soul Food (fried chicken, mac&cheese,
* Local fast food chains (In & Out, Hardees, Carl Jr, Popey's, etc...)
* Food trucks
* Fusion (Indo-Chinese, Korean-Mexican, etc.)
And don't feel you have to stick with just American food
* Chinese (Authentic)
* Brazilian (Steakhouse)
* S. American
* Mexican (authentic)
Basically anything she doesn't normally see back home. But also make sure to take her to a restaurant from her home too so she can share her food with you as well as get a taste of home.