I have an error coin that i don't know anything about. can someone tell me anything to help?

it is a walking liberty half dollar. the rim is not worn out ,but has a clean ring of cudaround it or something like that. also the edge of the coin has a crack that goes around it around it. it kind of looks like 2 coins smashed together ,but the coin thickness is the same as a regular walking liberty half dollar and the same size.