Not a restaurant but I feel like I've tried about everything from the fridge or pantry on a peanut butter sandwich.
Banana fluffernutter is as awesome as it sounds. Pickles are weird but not exactly bad. Jellybeans are kinda good, or maybe I'm weird. Peanut butter pepperoni is surprisingly good. But I especially love savory applications of peanuts (like OMG a good satay) so what you should really try is curry powder and a fried egg with scallions on your PB sandwich.