It seems like this should be under a different topic.
But like the person above said, Tractor Supply and local feed stores sell feed, as well as the chain Rural King. You can also order chicken feed on Chewy.com
I think you can even order off of Amazon now.
Depending on where you live, your local Walmart might carry feed and treats.
I agree with the others and use Tractor Supply as well as D&B supply