Photographs of pieces of paper with writing on them. Some of the most incredible things live written on the torn scraps of paper that didn't make it into the trash. They can be love letters, thoughts, quotes or a pertinent to-do list. So long as you found it somewhere (on the ground, a table or between the cans of soup at the store) and you don't know who wrote it.
If you find something in a mysterious foreign language, check out /r/translator
Check out /r/BookInscriptions too!