You would have to check with your local recyclers. So far the only thing that I have found to be recyclable from my shop is aluminum moulding ($.70/lb), and cardboard (the bike shop next door takes mine with theirs and turns it over to some charity that collects from all over town).
I tried to get someone to take my glass scrap, but no one was willing to pick it up (too heavy for me to deal with).
Scrap mat would seem like a no-brainer, especially 100% rag boards, but I've had no luck locally. I usually just give the leftovers to local art schools and classes.
Check with your local recycling place about the matboard. Where I live, the archival light colors go in mixed paper, and the darker colors go in with the cardboard.
Glass is a no-go here too,which is too bad but understandable...a lot of extras in the glass...
He was thrilled we called and said all of it can be recycled. They changed the way we recycle here where we don't have to separate what is being recycled which makes life easier for us lazy framers here.
We do give lots of boards away to schools, community centers, some day care (the ones without bevels). they actually like acrylic scrap too. the kids paint on it. It just seems we have more than the local community needs.
Thanks for your responses. I'm glad I have a place to go to to ask these questions.