Healthy Brown Bag lunches?

Question

Here's the deal. I need to lose 20 pounds by December 13th so I'm trying to eat healthier. My main issue is lunches. I bring a brown bag lunch to school everyday, I can't bring like plastic containers or thermoses because everything goes in the trash after lunch. Also I can't bring anything that will get gross if I leave it out too long, like american cheese.
All suggestions are welcome, i'm not allergic to anything eiher or like lactose intolerant

I'm 13 btw

Answer 1

piece of cooked chicken or turkey (4-6 oz)
celery and carrot slices
1 oz. assorted nuts
1 piece of fruit

Answer 2

you could bring:

celery and carrots in one baggy and a fat-free dressing in another.

baked chips

special k bars

dried fruit/nuts