If you have a cooler and ice, you can pack up almost anything.
This always makes me smile:
Chicken in a Sleeping Bag
(Or, use fish sticks in place of the chicken.)
Going with the crescent roll idea:
Make mini calzones, hot-pocket fillings (they can be cold) like mini meatballs w shredded cheese & bbq sauce, shredded chicken/bbq sauce & cheddar, pizza fillings (salami or pepperoni/cheese/tomato sauce, ham & swiss, turkey or chicken breast & cheese. Wrap any fillings up in crescent rolls and bake.Take along accompaniments like potato or cold mac salad, coleslaw, 3 bean salad.
Cold meatball pitas or cold meatloaf sandwiches
Chicken wings & dipping sauce
Fruit kebobs
If you have plastic containers or tupperware:
Guacamole & chips
Cold pasta salads
Cookies, trail mix, pretzels, brownies