Definitely if it's silver.
The mint did not make any proof coins in 1965, 66, or 67. "Special Mint Sets" with high-quality circulation strikes were produced instead. The dimes and quarters in them were made of cupronickel, not silver, and the half dollar was struck in low-purity 40% silver.
No silver coins were included in the 1973 Proof sets.
The only way this coin could have any silver (40%) in it is if there is a "S" mintmark on it. But not all 1776-1976 "S" mintmarked coins are silver. None of the coins made for general circulation have any silver. All the silver coins were only available from the Mint in special collectors sets. None of them were released into circulation by the Mint. So the coin is likely only face value.
The only Kennedy half-dollars after 1971 to have any silver are in Bicentennial (40%) silver Proof and Unciculated sets sold from the Mint. In 1992 the Mint started making "Silver Proof" sets again with 90% silver coins.
At minimum, they're worth the value of the silver.
If they are old enough yes, but all silver quarters are worth more than face value.
Yes, but none of the coins were made for general circulation. Silver Proof quarters sets and Silver Proof 10-piece sets were sold by the Mint, also the American Silver Eagle bullion coins were minted in 2006.
Silver dollars have .7737oz of silver in each.
Regardless of mintmarks if it shows any wear at all the value is just for the silver at about $1.30
value will likely be only for whatever silver it contains
All silver Roosevelt dimes are common, if it has any wear at all value is for the silver, about $1.75
Any silver dollar that has a letter or number added to the coin reduces it to the silver value only, about $12.00