I have a small flock, 5 chickens and 3 geese. The geese spurn almost all offered greens, but have an acre to free range and crumbles always available. The chickens are in a double run and gladly accept ear corn, melon, tomato, cabbage and some fruits, plus their crumbles. I avoid any toxic veggies and they will pick over other foods, and two hens will fly over the gate and free range too. Moderation is key, but I offer them these things 3-4 days a week. I have a healthy flock that gives good eggs, and are good birds. Well, the rooster is a jerk sometimes...
Cheers!