That's far too broad a question to answer without writing a small book. The US has issued coins with thousands of different designs, dates, and mint marks over the last 220 years, with denominations ranging from a half-cent to $20.
My suggestion would be to determine what type(s) of coins you're interested in so you can focus more specifically. For instance, are you interested in Morgan dollars? Large cents? Jefferson nickels? and so on.
There are many sites that are good sources of information. I've posted links to 2 of the ones that I've found to be pretty useful for values and rarity.
The FACE value is the same as all other US coins set by the denomination.
No, for silver coins as the value of silver changes the value of the coin changes. The same is true for gold coins.
1922 is the most common date of all Peace dollars retail values for circulated coins are only $15.00-$19.00 and high grade mint state coins are $20.00-$30.00
ALL us minted coins by stated value for a given year
They are worth about a buck apiece
Simple answer: The price of silver on the international market got so high that the coins were worth more than face value.
The FACE value is the same as all other US coins set by the denomination.
what is the value of these coins
No, for silver coins as the value of silver changes the value of the coin changes. The same is true for gold coins.
1792 quarter
1922 is the most common date of all Peace dollars retail values for circulated coins are only $15.00-$19.00 and high grade mint state coins are $20.00-$30.00
If you have the entire collection of coins that were minted that year and these coins are all in uncirculated condition, the value ranges from $8 to $12.
ALL us minted coins by stated value for a given year
No one can answer this question accurately. It depends on the coins!
They are worth about a buck apiece
Half Dollar, and A Nickel.
Gold plated coins are novelty coins with no collectible value and are not made by the US Mint.