I haven't read all yr responses so sorry to repeat.
My kids do breakfast with a fruit and grain and milk in a cup (or sippy)
so this morning was oatmeal with a cantalope slice (I make
a POT of oatmeal on the weekends, divide into single serving contianers, refridgerate,nuke in microwave 30 secs, serve!) I make oatmeal with milk, if I am in a rush and not prepared it is dry cheerios and milk in a cup. I have a just turned 4, I bet yr 3 can eat a bowl of oatmeal in the carseat with just a little mess.... eating in the car makes some kind of mess...it's okay!
Lunch after preschool is a pb&j/black bean & cheese tortilla/leftovers from night before.
My kids eat fresh raw veggies and fruits. So they love peas, broccoli, carrots. It is so quick and cheap and easy to steam these from frozen the night before and add to a tortilla rollup.
We ate spaghetti and steamed broccoli tonight for dinner. We ate the broccoli seperate tonight, but I mixed everything together and sprinkled cheese on top for lunch tomorrow. So we will eat spaghetti bake tomorrow at lunch.
My husband is the oldest of 4, raised by a single mom, and he talks about egg, cheese, and saugage/bacon tortilla rollups for breakfast in the car. As I understand, she would make huge batches on the weekends (like 50+ individually wrapped in plastic wrap, and frozen) they would microwave them and eat on the way to school.