My 3 year old son loves bambas, hazelnut (chocolate) bambas, he LOVES the pizza flavored goldfish, he also eats nutrigrain bars, those packets of cheese cracker sandwiches with peanut butter in them, Annie's mini bunny fruit snacks.
One really annoying thing he likes is these Hillshire snack small plates. They're like expensive "grown up" lunchables. Salami, sliced cheese, and these crunchy melba toast rounds. Under most circumstances, the kid would hate everything in there, but when he catches me eating one, he steals half of it.