Joann's once sent me a pack of MM alpha rub-ons that I didn't order. I contacted them about the order for some reason (maybe they left something out) and they told me to keep them.
This is NSBR but I ordered a Cherished Teddie from an ebay seller a couple of years ago. When I received it they had put an extra figurine in the box (different from the one I ordered). I contacted the seller asking if she had meant to do that or maybe she put it in my box by mistake. She said it was a gift because she delayed shipping the item for a few days. I didn't even notice the delay. I thought that was very nice of her. The original bear I ordered was a gift for a friend and I kept the second one for myself.