Corn. Cows. Beans, squash, berries.
We have great food here, honestly, and great wine and also bourbon is American. Great cheeses - Humboldt Fog is my favorite fancy cheese and it's American. It's just a big and diverse place. Italian - American food is its own thing and amazing. Cajun & Creole food are American cuisines.
I don't think there is one food that can represent the whole country because it's sprawling and diverse in every way.