I pack lunch for school everyday. I don't have access to a microwave, so everything is meant to keep in my locker for a few hours before I eat it. I don't store it in a fancy lunch bag - just a grocery bag.
This is what I pack (usually it's the same thing everyday):
A Liter of water, two liters in the summer
Bagel with Cream Cheese
Apple
Banana
Sandwich - usually a bun or rye, turkey, cheese, and other flavorings
Two yogurts (130g each)
A can (213g) of salmon with miracle whip (I like the flavor; you choose what you want to flavor it with). Note: this is prepared before I bring it to school.
During "the season," I'm on a diet where I consume between 4000 - 5000 kcal a day. Right now, though, since I'm not biking, it usually stays down around 4300 kcal a day. I threw in the salmon 'cause I needed a good source of protein. 213g can of pink contains a little over 40g of complete protein.
Usually I can't eat all of this at once. I space out the bagel and apple in between classes and save the sandwich, banana, yogurts and salmon for lunch.
Just what I bring.