Yankee Mattress Factory builds them here in western mass. They are amazingly well designed and built. I have three in my house.

They picked up the old for recycling when we bought new.

I realize now that I have no idea whether they recycle in their Agawam factory, or if they just took them to a transfer station.

Not the most helpful input to OPs question, I realize. But Yankee Matress seems like a Mass best-kept-secret.