Also check things like Craig's List or Nextdoor. Searching on "fabric" brings up everything from couches to motorhomes. Quilting narrows down a bit but you might get hits for slabs of wood or motorcycle seats.

Before we moved I replied to a "wanted" ad for fabric, she was looking for scraps to make baby quilts. After I chatted with her via a few emails and found she was a textile student she got a small pickup truck load of stuff! (She had the space.)

I still moved more fabric than I want and am watching for additional wanted notices. I'd be happy to let someone like you shop my stash for a project or two...

PS/Edit: Posting a Wanted ad is probably better than just checking the craft or free sections. I've responded to many more wanted ads than I've put up my available ads.

Icequeen is right that online want ads are probably the best option, but I think Facebook Marketplace gets more action than Craig's List these days. There's also Goodwill's online store which sells a lot of fabric bundles, or Destashify a marketplace specifically for individuals to sell fabric and sewing supplies.

I have a small amount of solid fabrics. As for the color brown, I have a fat quarter. I lean towards using tone on tones vs. solids.