A childhood belief about fairies

When I was younger every time I lost a tooth I would get a tiny letter that I had to read through a magnifying glass that the tooth fairy himself had signed! I heard some kids saying the tooth fairy was a girl, while mine was named Victor, so I asked my grandmother and she said that there were a lot of tooth fairies, and that she was a close personal friend of all of them. I still don't know how those tiny letters came about.