$14 (retail) in average circulated condition, up to about $30 if almost no wear is visible.
The is no 1921S Peace dollar; Peace dollars were not produced in San Francisco ("S" mintmark) in 1921. If your 1921 dollar coin is a Peace dollar, it was produced in Philadelphia and has no mintmark; if it has an "S" mintmark, it is a Morgan dollar produced in San Francisco).
The 1923-S Peace dollar is very common, circulated coins are valued at $16.00-$24.00 depending on how much wear the coin has.
Peace dollars were made from 1921 to 1935. An 1879 silver dollar is called a Morgan dollar after its designer George T. Morgan. There's more information at the Related Question
No D's in1928,but the S runs from $35.00 to $65.00 in circulated grades
The last Morgan dollars were dated 1921. Your coin would be a PEACE dollar. Please see the Related Question for details.
The is no 1921S Peace dollar; Peace dollars were not produced in San Francisco ("S" mintmark) in 1921. If your 1921 dollar coin is a Peace dollar, it was produced in Philadelphia and has no mintmark; if it has an "S" mintmark, it is a Morgan dollar produced in San Francisco).
The 1923-S Peace dollar is very common, circulated coins are valued at $16.00-$24.00 depending on how much wear the coin has.
Peace dollars were made from 1921 to 1935. An 1879 silver dollar is called a Morgan dollar after its designer George T. Morgan. There's more information at the Related Question
what was the value of a dollar in the 1960's
Circulated coins are $25.00-$90.00 Mint State examples are $150.00 or more
Your 1928 eagle silver dollar is actually a 1928 PEACE dollar, the first Silver Eagle bullion coin was made in 1986. But for this year of issue Peace dollar it's very important to see if there is a mintmark (S) on the reverse just above the eagles tail it makes a big difference in value. If you see the S a low value for the coin is $16.00 no S low value is $250.00. Take it to a dealer or collector for an assessment
Assuming the coin is circulated, the 1927-S Peace dollar is a more common date coin of this series. Most coins show heavy wear. For an accurate assessment of value the coin needs to be seen and graded. In general retail values for low grade coins are $36.00-$40.00, better grade are $41.00-$45.00 and coins showing almost no wear run from $60.00-$110.00. Values are a market average and only for coins in collectible condition, coins that are bent, corroded, scratched, used as jewelery or have been cleaned have far less value if any to a collector or dealer.
It should be valued at $15 - $30 depending on the condition of the coin.
No D's in1928,but the S runs from $35.00 to $65.00 in circulated grades
Morgan dollars were minted from 1878 to 1904 and in 1921. Please check the back of your coin. You have a Peace dollar rather than a Morgan.
The last Morgan dollars were dated 1921. Your coin would be a PEACE dollar. Please see the Related Question for details.
To date no 1928-S Peace dollar has been graded MS-69 by a major grading service, a few MS-66 coins have been certified but none higher. Value for the MS-66 coins is about $40,000.00