My sister-in-law left a lonely sock with us on her most recent visit, so we thought that we should have some fun returning it to her. (She also left a 10 House Point token from her copy of Hogwarts Clue.) What better way to return the sock than as a token of her emancipation as a House-Elf! I was able to find a "Hogwarts Acceptance Letter" Google Docs template from Taylor Walters. I modified it for the situation and have included the Word docx. I will update this instructable with her reaction when she gets it.
Have fun returning all of those forgotten articles of clothing to your friends and family.