It's from ancient Rome - it's called a 'Prutah' and it's from the province of Judea and Samaria during the prefecture of Marcus Ambivulus who ruled from about 9AD-13AD. It would have still been in circulation during the time Jesus was living there. No joke, don't ask me how I know all this. Hope this helps you out a bit
Google what underminer said it was and you can see values.As far as getting it authenticated the value of it may determine if you want to spend more than it is worth to get it authenticated.
stores in areas that have Christian retreats or campuses sell them as "widows mites" and make a killing off of unsuspecting women, often as necklaces or rings.