Because they were all struck at the Philadelphia mint
sliver dollar
Please look at the coin again, no U.S. one dollar coins were struck in 1929.
Assuming you're referring to the large size dollar coin, then it's Dwight D. Eisenhower on dollar coins dated 1971-1978.
The coin should not have a large 'R' on the coin, this has reduced the coins value to the silver in it.
By the date 1979 your coin is a Susan B. Anthony dollar and none of the SBA Dollar coins struck for general circulation have more than face value and none have any silver. Only proof and uncirculated collectors coins sold from the Mint have premiums.
racism
No Eisenhower dollar (1971-1978) struck for circulation contains any silver. Only some proof & uncirculated coins sold from the Mint were struck in 40% silver.
Check that coin again. There were no U.S. dollar coins minted that year.
The fact that the eagles wings are spread tells me it's a Morgan dollar. Value (regardless of mintmarks) is $30.00-$38.00 for circulated coins depending on condition. The 1921 Morgan dollar is the most common date of the entire series.
Simple answer: All coins are graded by the same scale. Circulated coins by how much wear the coin has. Uncirculated coins by how well the coins are struck.
None. There are no coins in a dollar. A dollar is a paper bill.
The Eisenhower dollars from 1971-1978 struck for an taken from circulation have no silver and only have face value. Proof and special collectors coins sold from the Philadelphia Mint are the only coins of this series that are above face value.