In my old community there was a little shop called "Bits and Pieces" that had been established as someone's Eagle Scout project, which took in crafting leftovers and you could go there and buy whatever for a minimal amount of money, and the proceeds went to a charitable cause (like, supporting senior citizens in the community or outreach or something). I wonder if there's something like that where you live? It had somewhat limited hours, but you could do one big run?
Its my understanding that places like Goodwill are able to sell cotton clothes that they can't sell to rag merchants, who then recycle it into expensive papers.
I would put 'em in a clear bag and send 'em to Goodwill or the like. If they can't sell them to a rag merchant, they might be able to sell them as craft supplies in their store.
You might contact senior centers or nursing homes in your area. Our senior centers are always looking for crafting supplies.
You could freecycle them.
Also scouts, brownies, preschools, and senior centers are always looking for craft supplies!