Fried bologna, scrambled egg, slice of tomato and onions with either mustard or mayo. Local place has been serving this called the Big Dog since the 1950’s.
Another simple classic in my area is a scrambled egg, mayo and fresh slice of tomato with salt sandwich.
Anthony Bourdain had a question he asked all kinds of people - if you could pick what your last meal was, what would it be?
Invariably, the person would answer with something their mom used to make for them when they were kids, many times a type of sandwich.
Mine would be a BLT :)