Here's an article about someone finding a copy of Son House's Dry Spell Blues in an abandoned cabin (and selling it to John Tefteller, natch).
http://www.goldminemag.com/article/casual-stroll-ends-a-collectors-dry-spell-for-a-son-house-rarity
http://www.goldminemag.com/article/casual-stroll-ends-a-collectors-dry-spell-for-a-son-house-rarity