Linda, I think that if everyone who farms or gardens on any level would practice "micro" agroforestry (I just made that up!) there would be a definite benefit to the local area environments! Little things add up after a while.
Hmmm... rats!? Wow. I have no idea how one goes about dealing with rats in the garden. They're such hardy, innovative, sneaky things! I wonder if there are certain herbs that rats don't like that could be planted between the rows of your corn and spinach?
Food (!) for thought!