The circle is damage and adds nothing to the value of the coin. But it's still 50 cents.
sadly their is no addec value so its worth 1 penny
This could happen if two planchets got into the die together (there will be a matching error with the tails side but no heads). It would have to be examined by an expert to verify that it is an actual mint error. That will cost you about $40 for an official certification. I don't deal with error coins often, but would estimate that such a coin would bring $50 or so if certified.
To correct several things: 1. This question has nothing to do with Child Law. There is a specific category for Coins and Currency that makes it much easier to find numismatic questions. 2. Coins are not printed or stamped, they are struck or minted. Books are printed. 3. The prefix is MIS- MISS refers to an unmarried girl/woman who hasn't moved to the use of MS. OK, that out of the way, you'll need to post a new question with more information, because there are many different possible mis-strikes. Please include a more complete description to help ID your coin. Thanks!