Silver coins of today only issued as commemorative or silver bullion coins (purchase them directly from US Mint), mainly due to increase of the price of silver. But before 1967 both US, Canada and most of the other countries had coins with silver content in circulation.
Silver coins value and silver coins price are affected by several factors, such as:
1) Rarity of the silver coin - rare silver coins are more valuable than more common silver coins, even if they look and grade identical and only differ in 1 year or by mint mark.
2) % Purity / Finesse of silver coin- there are no 100% silver coins, but investors are usually looking for coins with higher percentage of silver content and
3) Silver Coin Grade or quality: Silver coin value depends a lot on the coin grading. Usually, even the difference in 1 grade makes coins 2-3 times more expensive
4) Bullion Market value of silver as commodity : Silver coin value is also affected by price of the silver itself. This does not affect more expensive silver coins, but you can see it more in the price changes of the cheaper once.
Please refer to the Coin Values page for more information about silver coin values and latest silver coins prices.