Realistly, everything can't be recycled or made from recycled materials. The wood for frames and mat board can and are made from regeneratable materials (farmed).
Before they wend under Ivy Industries had a line of wood frames that were made from old beams from barns and factories. Barn wood frames today are actually made mostly from freshly harvested lumber and not recycled wood.
How about barn wood? I sell a lot of it. It is truly reusing material that would be thrown out. Another reclaimed material that can be used is hardwood flooring from houses that are being torn down. It is getting harder to get, people are starting to take bids on the really old stuff. It has huge character.
Recycled timbers from old houses etcetera can be very useable. Perhaps some of the furniture manufacturers in your area use a source that does not necessarily make itself known to framers. Alternately you could keep an eye open wherever you go and try to find a few good old sheds or houses (it can be a very addictive habit) and you can then supply yourself and a few others. oh, and the employees you typically need for ripping the place down will give you an endless source of entertainment...