Feed containers come with barriers to prevent the birds from perching above their food and soiling it. Select one or more of a type that you can clean easily. The feed store people are usually knowledgeable about these items and will be able to make recommendations if you tell them what kind of hens you are getting. You can add some scratch feed to this or buy whole corn to supplement their diet. The corn will make the yolks very dark yellow and full of beta carotene.
Chickens also appreciate kitchen scraps.
Greens of any kind, fruit peelings, bread, pancakes, even cooked meat. Chickens will eat anything. You will want to provide them with crushed oyster shell for strong egg shells, buy this at the feed store. Chickens also need grit to help them digest their food. A little goes a long way and you can scatter it in their yard or keep it in a feeder, buy this at the feed store as well.