Same here Brad, re: varying degrees of success. It's mostly a fun kid project that teaches them that it takes work for food. I keep reinforcing into them everything has a price one way or another. Your sweat, your money, everything we consume has it's price. That's why we don't waste.
"Yea, Dad, I know, I know. You've said that a million times."
"Then why is half your sandwich in the garbage?"
"I was full. Can I have a snack?"
"Sure, here's half a sandwich."