Along those lines, I have come across a some websites (i.e.; FreeCycle, Facebook, Nextdoor) that have a free section. I've see various furniture listed made with wood.
My wife likes to walk the neighborhood and on occasion has made some good finds. The latest was a king size bedframe with the headboard and footboard made of creamy poplar.
Also, a couple of our friends, knowing I do woodworking will call us from time to time, letting us know if someone has put something on the side of the road that I might be able to salvage for wood.