I'm assuming that he is under 10, if he isn't, it's time to have a frank talk with him about what you can afford and how he can help you figure out what he will take. Boys have a tendency to let you do things for them until you tell them they have to do it themselves. I know it's amazing what I still have to tell my husband to do
LOL
thermos-
Hog dogs in a thermos, buns and ketchup packages
alphagetti and a roll with butter and cheese cubes
fruit smoothie and crackers and cheese
Munchies-
carrot and cucumber (broccoli, cauliflower) and dip (salad dressing)
mandarin oranges, berries in season with whip cream, apple with peanutbutter or carmel sauce to dip in, melon chunks
home made muffins or cookie's with icing on top.
Sandwich fillings-
tuna, mayo, cheddar cheese and ketchup, I know sounds gross but kids seem to like it.
mini salad rolls (they're like really small sub buns) with the sub fixings he likes.
Cold things-
Pizza
chicken strips with sauce to dip
cereal and milk in seperate containers, or simply just the cereal
hope some of these help
Jo-Ann