For whatever it's worth, I've eaten PB and jelly (all sorts, including mint), PB and mayo, PB and Kraft Salad Dressing, PB and honey, PB and catsup (or ketchup), PB and bananas, PB and carrots, PB on toast, and PB and yellow mustard. I have also eaten and enjoyed mayo and banana sandwiches.

Some of the PB combos above are good. Others I don't recommend, but to each her/his own.

My first rule of cooking: Nontoxic in, nontoxic out -- inedible, maybe, but it won't kill you.