Chickens offer a lot of bang for the buck, or is that cluck!
They are a double food source; eggs and meat.
They will reproduce rapidily ( keeping a few banny hens will further this as they will sit on anything; even duck eggs to hatch them and they do it often!) .
Chickens will eat anything but bone so you can feed them your waste from dinner,dinner prep, weeds from the garden,damaged vegitables and such . They also help by eating insects and if at all possible should be allowed to wonder in the garden. They mostly will not bother vegtables that are not damaged but prefer the rotten ones.