I've got a lump on my head. On the hairless area right behind my ear. It's about the size of a nickel, kind of hard, definitely not attatched to my skull because I can move it around, and it itches from time to time. I've had it for about a year I guess. Any guesses on what it might be?

Hi Jessica,
What you are describing is probably a lymph node, part of your body's immune system. It is probably not much to worry about, though if it continues to persist or bother you, or if you develop a fever at any point, it would be worth your while to have a doctor look at it.
Take care. :)