Hi P.,
I really don't have a lot of suggestions for actual food for school lunches, but I have ideas for lunch at school.
I am a lunch lady, I have seen it all.
The first piece of advice is talk to the person at school who is in charge of the cafeteria, they have title's like Cafeteria Managers, Head of Cafeteria, ect. Nine times out of ten they have their own phone lines, leave a clear message about your child's allergy, and be prepared to back it up with a note from a Medical Doctor. We have to follow proper steps if your child has a allergy. (Even me, my son can have no dairy products and it is on record at the school) We do see it all and approaching the lunch program (even if you plan to bring lunch from home every day) is the first step.
Next pack lunch in containers that are easy to open. If your child has to wait to get help opening his thermos that is time cutting into his lunch eating. The law at some schools is they only have to be in the cafeteria for 20 minutes. They need the time to eat. Which we all agree is horrible for little ones.
Realize that your child may not have enough time to eat everything that you send, don't ask why not or tell him to eat it all that really puts more pressure on what can be a very stressful time.
The first week or two of school the lunch room can be overwhelming, lots of people, noise, bright lights, ect. Ask your child how it was, if it was overwhelming talk to him about it. I promise for most children it will become nothing.
If after the second week he is still having a problem call the school cafeteria and explain, we are nice people who really want this to be a positive experience. A private tour, or just meeting the lunchroom staff really does help.
(We had one girl who was so scared that she was not eating at all at school, she came in met us, and we made a point of just waving to her once a day and she was fine and invited us to her sixth grade graduation)
Do not go to lunch every day with your child. It is wonderful when we get parents in to visit but if you plan to be there every Friday guess what happens when you can't be. Visit for a special occasion, or surprise your child but not constantly. (Make sure to check with the school on your schools visitor policy, you may need to notify in advance, or just check in.)
Finally, find out if your child has access to snacks for sale in the cafeteria. We sell goldfish, yogurt, milk and juice. If you want to limit the amount your child buys let the manager of the cafeteria know. I personally allowed my child to spend 50 cents a week (excluding milk).
Opps here is the last part... My daughters sample lunch:
Milk, hard boiled egg, crackers, cubed cheese, cubed meat, half an apple, carrot sticks, piece of bread, water, grapes, raw green beans. What ever she does not eat for lunch she has after school for a snack. (She's 14)
Good luck!