I don't mean to come across sounding like a smart aleck, but if you are that into recycling, you could attempt to return the wood blocks to the place where you purchased the stamps. They may not tell you, but I bet they would re-use them. Not something I would do though.
But, as you are trying to find somewhere to give/send the wood blocks, realize the time/expense/effort you are putting into it. Is that truly worth it just to recycle? Something to think about.
I have to admit, that I am not big into recycling, but I don't purchase stamps on wood anymore. Too much effort/time spent in unmounting.