You can post wanted ads on Craigslist or Freecycle, although some freecycle groups want you to post Offers before requests.
I have used both, freecycle seems to attract fewer scam artists as no money is involved.
I have been making quilts for over 30 years and just LOVE that quilting is going back to its roots and quilters are recycling clothes to make quilts the way our ancestors did!! I had not realized this before finding the QB.