I know one way they got there. Some one who did not know the value of those items donated them on behalf of the owner. One of my colleagues married a widower who's wife had been a quilter. He cleaned out his house in preparation to sell it and gave all her stash, books, tools and thread to Goodwill. He just wanted to get it out of his house. I about cried when I heard about it. I would have paid to have even some of her quilting "stuff" and carried it all to my home for him. I have to look at is as someone else needed those things more than I did, at a bargain price.
Enjoy your find and pour blessings on the one who picked them out and the one who gave them away.