The best place to check any coin valuation, apart from seeing a numismatist in person, is to check on various coin valuation websites such as Jake’s Marketplace (jakesmp.com) or mycoincollecting.com. It is likely that the coin is worth something but as a relatively recent coin would not be as valuable as one which is older. Silver Eagles bullion coins came into inception from 1986, so it cannot be of this sort if the date mark is 1981. Perhaps it was a proof coin and the design would later become the basis for the bullions but as far as one can tell more information is required as most coins have American Eagles on their tail side; detailing any other features of the coin and confirmation of the year would be beneficial to a numismatist. The quality of silver may well impact the price, of course, but there is no evidence of a coin called the Sunshine Liberty. The best thing to do is to look for any other coins in your collection and investigate whether any of those are more valuable; Internet auction sites are full of amateur numismatists so, having checked the calibre of their selling history, it might be worth putting the coin on one of these sites before seeking a professional valuation. Indeed, the more research you do yourself the better the amateur numismatist you become as well.
1981 Silver Coin Said To Be The Sunshine Liberty Has American Eagle On Back And Is .999 Fine Silver Is It Worth Anything?
Your coin is a proof coin made by the government for collectors. In MS-65 (it should look like it was just made) it is worth about $10.