ISO a Gently Used Mattress, Twin or Full

Hello Listserv, I recently helped a dear one move. Her old house had furnishings included that she was unable to bring with her. As a result, she is currently living without a bed. She was hoping to find a cheap or free gently used mattress, either twin or full sized for a small space. Does anyone have a mattress like this that they are looking to part with? Thanks for your consideration! Your neighbor, Sara