I'm always going around in the winter to pick up leaves from what people leave in the front of their houses for city pick-up. This saves me tons of money on mulching, tons...since I mulch the vast majority of my yard. I always go thru the rich neighborhoods, that way I know I'm only going to get yard waste and not other trash thrown in -- I've learned my lesson well on that point.
Here in Florida, gardeners love buying potted mums in Christmas, so as I was picking up leaves one day (in January) I saw a potted mum plant laying on the curb for city pick up, these plants cost at least $20, but this one had a really fancy pot, so probably more...I don't do container gardening, so I planted it in my garden and it's now coming back to life and even blooming.