I printed out the Walmart return policy in English, took it with me, and when the clerk said I needed a receipt, I showed him the policy. End of argument. He took it back and I got a credit.
To those who said I should keep receipts--of course I know that. However, this was purchased a while back and I don't keep receipts for 90 days. Nonetheless, they need to honor their policy which is to take returns without a receipt. This was a paper item in its original wrapper.
I am keeping that printed out policy in my files should I ever need it again.