Coin Collectors of Reddit, can you help me?

I don't know if this is the right subreddit, if not i'd be happy to move to that one. BUT! The other day I was walking around at work and found a Silver Dollar, 1776-1976 silver dollar. I don't know if it is the silver coated or the legit silver dollar. How can I tell? Also, how do I tell the value of it, it's not in great shape, so I'm not expecting much. Here is a picture of it http://i.imgur.com/RUccB.jpg