Chickens like to forage. So plant with this in mind.
Here are some ideas on how to structure your gardens and chicken pens with this in mind.
http://thegrownetwork.com/how-to-grow-happier-chickens-and-healthier-eggs-from-seed/DO NOTE that allowing your chickens to free-range also exposes them to predators like coyotes, hawks and "wild" dogs.
Conversely, my dogs would serve as watch dogs over the chicken during the day... If I kept them well fed so they didn't see the chickens as a quick snack.
If you grow grains with the intent to feed some of it to chickens, DO NOTE that sprouting the grain and allowing up to six inches of stalk will greatly increase the nutrient value in the seed. Even if you don't grow your own grain, now, the grain you buy can/should be spouted as feed stock.