Ooh, tough. (side note: I suggest a picnic with the foods you just listed. Like, now?)
Smaller than a marble? Gotta be something sweet, as savoury foods (other than condiments like salt etc which I wouldn't eat alone). So it's gotta be a sweet. At first my answer was simple: Minature PB cups. But on inspection, they're bigger damnit. So, chocolate raisins? Minstrels? Maltesers? Or do I cheat and just say Celebrations? No no, I know my answer. Screw Chewitts and Werthers Orginal, when I have the choice of M&M PEANUT BUTTER FLAVOUR. I've only had them a few times due to their import-necessity (12 times the normal price? Hey, WHY NOT. :/ ) but I love them. They have something to them that Reeces Pieces can't quite do, and the crisp chocolate shell with a smooth PB center is DIVINE. I don't even particularly like PB but these are something else. AMAZING.
Favourite flavour TIC-TAC?