Just recently I had posted a book review for Handwritten Recipes by Michael Popeck for work. Popek is a used book seller from New York who has rescued recipes found in various books that have found their way into his shop. In his book, snapshots of these culinary bookmarks are arranged with a photo of each book in which it was found, telling a story of things forgotten between the pages.
At the library, where I work, we are constantly finding all kinds of documents and forgotten scraps deposited between book pages. There are photographs, loving notes signed from Gramma with love or cards from a special aunt. Medical appointment memos, bills yet to be paid and yes, sometimes we have even found cash. All the before mentioned are returned to their rightful owners.
Sometimes things get missed at check in and they remain in the item long after a previous user can be found. These things go to lost and found, other personal information that is unclaimed is always shredded and the orphaned photographs are saved by a staff member with the hopes of someday recognizing the person in the library. So far, not one of her growing gallery of pix has not been successfully reunited with their kin.