Your chickens will be healthier and their eggs will be healthier for you to eat if you can get some green feed into them. Green feed is the chicken equivalent of the dark leafy greens that are so good for people. It can be grass, kale, collards, chard, spinach, alfalfa, clover, wheat grass, oat grass or other things. It can even be sprouts, if you let the sprouts grow leaves. That's the main thing that isn't in a bag of chicken feed, that's a natural part of their diet. That's what makes animals and chickens raised on pasture healthier and healthier for you to eat.
A little animal protein or non-soy protein can be good for them, too. If they free range, they eat a lot of bugs to help with that. Plus worms.
You can also give your chickens a variety of different foods from your kitchen or garden. They can eat most of the foods you can and a balanced diet for them is similar to a balanced diet for you. That just means, don't give them a huge amount of only starchy foods or fatty food all at once and unbalance their diet. At least, don't do that regularly. They are small creatures.
The main foods to watch out for from your kitchen are chocolate, avocados or a large amount of anything really salty. They can cause problems for the chickens.
Greens, vegetables, fruits, herbs and spices all have a lot of chemical compounds in them that do good things for people, animals and chickens. Depending on which one it is, they can fight cancer, fight viruses, fight bacteria, boost immune systems, reduce inflammation or provide a better fatty acid balance in the body. Plus, you get a wide variety of vitamins and minerals from them.