The first place I have seen carts with little metal attachments was BJs. These attachments hock into each other and a take a quarter to detach them from the chain. Most people will return these carts to get their money back, but not everyone. That is your opportunity. If you find any stray carts floating around at places like BJs and Aldis, by all means, return the cart and take your reward. Every little bit counts. Many malls also have "smart carts." These little strollers are available for rent and bringing them back refunds part of the rented investment. The rewards vary 25 cents, 50 cents or even as much as a dollar. This is an easy way to earn a little extra money when you go to the mall.