Plus the things other people have mentioned....
baked apples with cinnamon and brown sugar
a green pepper stuffed with tuna mayo (okay, not for everyone- but my daughter loves it)
Feta cheese cubes and cucumber
crusty bread with simmered rhurbarb spread on it
fruit salad- my kids like bananas, peaches, pears, and cranberry
berries are 'superfoods' and obviously quite expensive, but if you buy them frozen not usually too pricey (we buy ours at a local farmers market- you can buy per kg) I use them in quick breads, we eat them plain, mixed with yogurt, and put on cereal
My son likes dry Weetabix- obviously I don't recommend this

avocado- partially peeled and eaten with a spoon
Hummous on english muffins with black olives