Heather -- There are many silver coins with the Indian and Buffalo pattern. They are all marked with the amount of silver they contain. Yours has 1 troy ounce of pure (0.999) silver. For a similar coin, but with 2 troy ounces of silver, see this page:

https://coinquest.com/cgi-bin/cq/coins.pl?coin=15251

Your 'coin' is not really a coin, since it cannot be used in commerce. Officially, it is a 'medal,' but it is still worth something. It is worth its weight in silver. If you look on the internet, you will find silver is selling today for about $18 US dollars per troy ounce. So that's what your medal is worth, $18. If you sold it to a collector, he or she would pay about $18, maybe a little more, maybe a little less.

BTW, when dealing with precious metals, like silver and gold, one troy ounce is the same as one ounce, the 'troy' is understood.

In recent years, the US Mint has issued Indian and Buffalo pattern coins (really medals) in pure gold. They contain 1 troy ounce of gold, and are therefore worth about $1700, which is the current selling price of gold. Very pretty!