WalMart def gives them away. You might run into a different policy store-to-store, but it's a lot about timing. I know when I was a supervisor there, I was giving customers tips on which boxes were strong or weak or could stack safely.

By the way, it's the boxes that laundry detergent come in. Those can be packed with the heaviest stuff and still stack a mile high. Perfect for dishes or glassware.