Well, glad I asked, folks.
See, I'm sitting here trying to come up with the most disgusting American food I can think of (not that anything mentioned here has been disgusting

), and the best I can do is my mother's specialty. Haven't had it when I was a kid, but it is....ta da...
Peachy Cheeseburger Pie.
This is a pie crust filled with sloppy joe mix (hamburger and canned tomato sauce). Then on top, in a little pinwheel shape, are half slices of Kraft american cheese and cling peaches. I think she baked it for awhile.
Fellow Americans, surely we have more disgusting food to claim as our legacy than this?
Edited to add: I'm not saying English food is disgusting. I'm saying my mother's peachy cheeseburger pie is disgusting. For the record.