The best purchase I made was a small soup size thermos so I can send a hot lunch to school for DS1 a few times a week. You put hot water in and close it for 5 minutes. Then, I heat up the spaghetti or mac n cheese in the microwave. Dump out the water and put in the food with a plastic spoon.
Each day DS1 and I talk about his lunch and what he likes/doesn't like. He's not allowed to throw away food but rather be honest and tell me what he likes and doesn't like. I also always add in besides fruit, etc. 3 oreo cookies.