Towels or fleece are usually preferred by shelters since they wash so easily but I have found that shelters usually accept anything. As someone wanting to improve their FMQ, I think it is a brilliant idea. Yes, go ahead and use the poly. I have a friend who makes dog beds for shelters. She collects ALL our tiny pieces of fabric from quilting that normally would be thrown out. Hope she can use an old worn blanket. I prefer to recycle as much as I can.