..... Before you give them peanut butter jelly sandwiches, you need to see if the school even allows that. Because, MANY schools are "nut free/peanut free."
Next: make for the kids, what they WILL eat. Because, even if you make a pretty/cute/fancy/gourmet lunch, if the kid does not like those things, they will NOT eat, at all.... even if... they are, hungry.
I work at my kids' school and supervise the kids at lunch, and I know this.
It doesn't matter how cute the lunch box is or how fancy or gourmet or balanced the home lunch is. IF the kid does not like what is in the lunchbox, they will NOT eat. AT, all.
So, the gist is: pack what your kids, WILL, eat.
If your kid eats a ham sandwich and that is what they want all month, everyday, fine. MANY kids bring the SAME thing, everyday. Because, they like it and eat, it. You are not making home lunch for what others may think of it when they look at your child eating in the cafeteria. You are making the home lunch, for your child, to eat. Some parents, pack a lunch according to what they think others will think of their kids' home lunch. But this does not matter.
The main POINT, is that, your child have something they WILL, eat.
I have seen, MANY MANY kids, just sitting there, not eating at all because, as they tell me "My Mom made something I hate." or "My Mom made something I don't even like..." so then I tell them to tell their Mom so that Mommy can make something they like and will eat. But sometimes the kid tells me "I can't tell my Mom what I want or like. I don't have a choice."
ASK your kids, what they like. What they will eat.
And no, not candy or junk food.
And, get a proper lunch box, that is insulated and which you put in a blue-ice, ice pack in it. So many kids I see, their lunch box is not even insulated and not even with a blue-ice cold pack in it, and their food is not kept cool properly. One kid once even brought his home lunch just in a plastic grocery bag with no insulation and no ice pack in it. And his home lunch was left over dinner from the night before... it was fish & veggies. We couldn't let him eat it. Because, fish is perishable and it was not even kept cold. We had to toss it, inform the Mom with a note home, and we had to give him a school lunch. So that, he could, eat.
Instead of peanut butter, there are alternatives as well:
ie: cookie butter. Or Sunflower butter.
You need to talk to your kids, see what they like and will eat. THEN, plan your home lunches.
And, you do NOT have to pack, and entire 7 course meal.
Nor tons of "sides."
Many kids cannot eat all of what is in their bag. For example. And some kids even will sit there, stuffing their mouths eating and force feeding themselves and be all stressed... because they tell me that "My Mom said I have to eat everything, or I can't leave the cafeteria...." or "My Mom gets mad if I don't eat everything...."
So the bottom line is: pack the amount in the lunch box, that your child can, rationally eat. Per your child's appetite or age or ability.
And because, if a kid does not eat their home lunch, then ALL DAY long at school, they will be hungry/tired/unfocused/irritable.... because the have no fuel in their body.