While I have not gone to the expense of doing this, there is an Ameraucana breeder that I know and trust that says they put their newly hatched chicks on a bed of alfalfa pellets. She says they loved them and when the pellets get too soiled for the chicks to be on, she says they are worth their weight in gold to others as compost.
My birds normally free-range so I don't worry often about them getting enough greens. However, during the time they're in breeding pens, anyone knows that it doesn't take a few birds long to turn a nice piece of sod into a dirt floor. The church we go to has vegetables, bread items, fruits, and other things that they give away. Often there are items that are too far gone for human consumption - at least IMHO. They gladly give them to me to feed to my chickens. So every Sunday my birds get treated to spinach, lettuce, cabbage, carrots, pears (they love pears!), squash, various melons, peppers, kale, and other greens that I can't even remember what they're called.
I'm not suggesting you start going to a church just to get free treats for your birds of course. But you might check around at some grocery stores or open markets to see if they have any "give aways". Just let them know your birds would gladly have them and it's better than a dumpster.
Hope that helps.
God Bless,
