At that age, my boys really loved "egg-casserole" for breakfast. And it was great, because you could make it and freeze portions. Take out what you need every few days.
- butter a 8x13 casserole dish
- cover bottom with bread (any kind) - remove the crusts first
- top with cheese (any kind, slices, shredded, etc.)
- top with whatever else you want, I would sneak some veggies in here (chopped brocolli, sausage, bacon, other meats, anything!)
- whisk 12 to 18 eggs, and then pour over the top
- bake at 325 for about an hour
- let cool, chop into appropriate bite sizes pieces
- freeze what you want, take out as you need it
I would make 1 a week for my twin boys, they ate it almost every morning for 6 months. Very easy to transport via containers to daycare.
Other ideas for breakfast...how about just a protein and fruit?
- Sausage/Scrambled Eggs/Cheese/Yogurt/etc.
- Apples/Grapes/Kiwi/Banana/Blueberries/Strawberries/etc.
For lunch - how about just a protein, a veggie, and a fruit?
- Beans/Chicken/Turkey/Meatballs/Hotdog/Cheese/Yogurt/Pasta with cheese or meat inside/etc.
- Peas/Green beans/Carrots/Brocolli/Sweet Potatoes/etc.
- Apples/Grapes/Kiwi/Banana/Blueberries/Strawberries/etc.
For Sweet Potatoes, I like to cut the skins off - chop them into tiny cubes, then cook on a plate in the microwave for ~5 or 6 minutes with a handful of water thrown on top. You can mix them around with a spoon half-way through. You get firm little cubes that are great finger foods and are easy to transport.