How much is the value of a 1879 silver dollar coin?
Depends on whether it’s rare, depends on the face value, and it depends on the condition it’s in. The best way to find out is to go to eBay and try to find that exact coin (there are probably millions of coins for sale there, you’ll have little trouble finding it). That’s how you find out what people are willing to pay, and that’s what it’s worth. (Silver does very well on eBay. I sold some Kennedy halves for a lot more than I think they were worth, your coin is easily more valuable if it’s in decent condition.) Legal definition of “fair market value”: The price a reasonable buyer is willing to pay to a reasonable seller.