I used to make a lot of lunches for our family every day. I liked having all the disposable sacks, bags, etc. so no one brought thing home to wash. I have changed a bit since then. Now we are more careful about our carbon footprint. I have done the following to be less wasteful:
1. Use a lunch box or reusable bag instead of paper bags.
2. Bring a reusable water bottle with you instead of getting juice boxes or plastic water bottles.
3. Use containers instead of plastic bags for carrots, grapes, snacks, etc. Sometimes we send leftovers in containers instead of disposable bags.
4. Don't send paper napkins or disposable silverware. Once you get used to using cloth napkins, the paper napkins just don't stand up to them. If you are worried about losing a piece of your silverware set, get some cheap utensils at garage sales or thrift stores. That way you won't worry if it gets lost.
5. For sandwiches, you can try wrapping it in a cloth napkin. At Zero Waste Home, they show how to fold your whole lunch in a big piece of cloth. I wouldn't try it if you are taking soup....