I'm a daily-treater of 4 free-rangers (recently thinned my flock of 7 to make room for 2 pullets that just started laying......and got 3 chicks earlier this week, so will be back up to 7 in the big house soon enough).
Treats here consist of meal worms, scratch, a small bit of cracked corn, table scraps or left overs. The list of things I give is pretty vast and varies with the season. We fish, so I always keep some tiny or undesirable fish just for the birds. I throw them on the grill whole and flip them out onto the ground and step back to watch the feeding frenzy. They get the leftover minnows, wax worms, leeches, etc too. I have a heated bird bath that I leave under the faucet in the winter. After one of our ice fishing trips, I dumped the leftover minnows in the bird bath and the chickens went nuts chasing them and plucking them out of the water.
Along with the fish, their other favorites have to be string cheese and bacon scraps.....well, any meat scraps. I cut the fat/grizzle trimmings into small pieces and they absolutely love them.
This winter when the polar vortex was bearing down on us with -60 wind chills, I'd take warm cooked oatmeal laced with yummies like pomegranate seeds and bacon crumbles out to them morning and evening to warm their tummies.