Yo, Hubcap -- You have what is commonly called a silver 'round,' or silver art deco round. They also come in squares and rectangles and are then called 'bars'. Legal tender silver coins issued by the US government are called Silver Eagles which you can see at this CoinQuest link.
A silver round is simply a chunk of pure silver struck into a coin shape with an eye-catching pattern. They are collected and they are also used for investment. There are thousands of different patterns.
Value-wise, silver rounds almost always contain one troy ounce of pure silver and are marked as such. These sell retail for a few dollars above the silver 'spot' price. Find silver spot at kitco.com. If you want to sell your silver round to a dealer, he or she would generally pay a several dollars less than spot. The difference between the buy and sell prices is the dealer mark-up. Figure a dealer mark-up around 40 or 50 percent for a single round, but much less percentage as the number of rounds bought and sold increases. For large purchases, say over $5000 US dollars, mark-ups can be as low as a few percentage points.
If you are buying silver solely for investment and not for collecting neat coin artwork, US Silver Eagles (or equivalent coins from other countries) are a better bet. With a US Eagle, weight and purity of the precious metal is guaranteed by the US government. With silver rounds there are no guarantees.
Read our write-up on evaluating bullion coins (both silver and gold) at this CoinQuest link.