1 dollar
It is worth about $10 in good condition and about $20 in mint condition.
$20
The US did not mint a dollar coin in 1968, therefore you don't have a 1968-D silver dollar.
The U.S. didn't mint any silver dollars in the 1940s.
The Carson City Mint opend in 1869
A typical Mint State coin is about $50.00
as much as you can get for it.
The U.S. didn't mint any silver dollars in 1946.
There were no silver dollars issued by the US Mint in 1964.
It is worth around $25 in its original condition, having the original black "clamshell" case will help. This coin is made of 50% silver, meaning it has .357 of an ounce of silver.
A 1884 Silver Dollar - aka - Morgan Dollar - is worth in good condition (G4): $18; if its mint state is MS60, the value rises to: $40.
A 1901-S Silver Dollar - aka - Morgan Dollar - is worth in a mint state of AU50: $225.00.