I asked several local grocery stores last summer for expired produce but they wouldn't give it away for fear of people eating it and getting sick, didn't want to get sued. I tried to assure the produce manager it was for chickens but he said they just couldn't do it.
I just watch for stuff on clearance in the produce section now, just bought them some heads of lettuce for a quarter each.
I wonder if a group of folks (local BYC'rs or homestead farmers or even big farmers) got together and formed an organization to set up a contract with the local grocery stores to deal with all their expired produce if they would go for it. Of course, the hassle of organizing folks like that, but perhaps a more formal agreement (with non-sue clauses) would set more stores at ease.