I had a worm farm when I was little. We grew them to use as perch bait, and also to eat compost.
We had a plywood board and pine needles on top of the dirt. We would put food scraps out in the pine needles, and then laid the board over the stuff. It grew some big worms, and was very easy to manage.
When we needed to add to the compost pile, lift the plywood board and add more food scraps.