Chickens will eat just about anything, so if you have any prized plants in your garden, be warned you may not have them for much longer! (as I have found out over the last year) And yet they haven't even made a dent on the dandelions!
I feed mine a lot of kitchen scraps (not meat though) but don't give them stale bread unless you soak it in water first, apparently it can swell up in their crops.
They are particularly fond of left over cooked rice or pasta, tinned sweetcorn and grapes, it still cracks me up when I see one of them charging up the garden with a beakful of spaghetti and the others in hot pursuit!
Have fun!