I have an old solid rear/front mountain bike from Marin circa 1997. Little to no use but the components are pretty rusted up, tires dry rotted, etc. It is chrome colored 7000 series aluminum frame, yellow forks and other accents. Frame I think is a size medium or large. Would fit someone in the 5-8 to 6ft range, I imagine. I *think* I have some tires lying around that would fit it, or you could throw in some new tubes and run the ones on it. Spray some oil on the chain and shifters and rip up the rail paths. This was a cheap bike back then, but in too good of shape to throw away. If no one claims it, I'll probably throw an hour at it and make it ride-able and leave it in the local park with a FREE note.
I can meet you in the Leominster area or out toward Ayer.