Sure. Here are some of my preschool or school lunch ideas:
I always pack a fruit or veggie+protein+main dish
Fruit: like strawberries/blackberries/sliced grapes or even apple sauce
Veggie: Carrots/salad/cucumbers/broccoli/corn
Ideas for Protein: nuggets/Fish sticks/Cheese/deli meat (can find without nitrates its better for them)/Fish/Egg
Here are some of my ideas for main dishes:
Yogurt +cereal
Bagel and cream cheese
Pizza created from a pita+tomato sauce+cheese
Macaroni and cheese
Noodles with butter salt and cottage cheese
Crackers with cheese
Brown Rice cake sandwich with Peanut butter (or sunflower seed butter if school is nut free) and jelly
Brown rice with meat or cheese (can buy microwavable rice)
Nuggets with rice
Fish Sticks with rice
Fish with rice
Toast with butter and an egg
French Toast or Pancakes with egg
Give them yogurt cereal and fruit separate and have them make a yogurt parfait