It's not just Planners' offices, but architects & other specifiers too, although I do gather it's a lot harder to get (for example window) samples than it used to be. Our Architects dept office used to clog up with them. Slightly embarrassing incident once when, after aeons, the rep did return for his sample, and it had to be removed from its installation in a colleague's garage wall!

Good idea though. Probably something like Freecycle is a good vehicle. I think the limitation with a lot of potential recycling is the 'admin' involved in getting the materials someone doesn't want to the person who does want them. I understand a lot of potential wood recycling schemes have fallen at the first hurdle because they have not been economically viable in the long term.