I need kids lunch packing tips / ideas and recipes... if you don't mind to share!

I am thinking of summer camp and this is pretty much the common set of rules:

- There will be no fridge. I will pack lunch with an ice pack;
- Lunch boxes will probably be placed in a "shaded area in a 'not-very-cold' ice chest";
- No heating up available;
- No nuts, of course;
- Ideally no mess, but I've talked to one director and they said they allow utensils.

All I can think of is sandwiches and sandwiches... cold sandwiches too, and some fruits and salad, that's it. I am not a big "sandwich maker" so I don't know what else to make other than sunflower seed butter + jam , and grilled cheese! It would be so boring and non-nutritional.....

Any ideas, recipes and tips to share for a variety of lunch ideas that can last us through summer? Thank you!