Corn should also be part of your homemade chicken feed, although you should use caution in the summer as it tends to heat chickens up, which isn't a good thing on a hot summer day. However, it's a wonderful way to help them stay warm in the winter.
Other grains to include in the recipe are a combination of other grains such as barley, millet, quinoa, oats, kamut, etc.
For added protein and variety, as well as nutritional benefit, add legumes such as peanuts, lentils and split peas.
Again, for added protein and variety, throw in some seeds to the mix of chicken food. Such things as sunflower, flax and sesame seeds. A great benefit of flax seeds is that they've been shown to help raise the Omega-3 levels of the eggs that hens lay if they've got flax seeds in their diet.
You can get this in granule form and adding it into the food (in small amounts) helps with egg production, healthy growth and the ability for the chickens to maintain the weight that's right for them.
Misc Other Stuff
Don't forget to also include calcium and grit in your chicken diet plan, as they'll need both. This doesn't need to be mixed into their food, as it does better in small, separate feeding dishes for them to eat as they need it.
You also might like to consider adding diatomaceous earth to the food to help control internal bugs (see here for diatomaceous earth uses: overall health, dust bathing, and mite and lice control and coop cleanliness.)
If you want to try your hand at making your own chicken food, start in small batches. Chickens are individuals with unique tastes. (I have a chicken, for example, who hates all fruit, but loves green veggies although most of the flock around her gobbles up both any chance they can get.) With a little trial and error, you'll find out what combinations your chickens like best and it will help you formulate the perfect mix for your flock.
You will find more information about feeding chickens here.