This question comes up fairly often and is a common misunderstanding. US $1 coins made up till 1935 aren't called "eagles" and they don't contain 1 oz of silver. They were ordinary circulation coins made for use in daily commerce. While they do contain silver, it's not as much - about 3/4 of a troy ounce.
"Silver eagles" are modern (1986 and later) coins sold by the Mint as investment pieces, not for spending; their value is linked to the current price of silver and the "$1" value is purely artificial.
The coin you have is frequently called a Morgan dollar after its designer. Its value when minted was in fact exactly $1 because silver was much cheaper and its price was controlled. Today it has value not only for its silver content but for its interest to collectors. There's more information at the Related Question.
There is 24 grams of silver in a 1891 US silver dollar.
Retail is $17.00-$38.00 for circulated coins
Assuming the coin is circulated and has no mintmark, retail value is $18.00-$38.00
A 1891 U.S. silver dollar is a Morgan dollar. This series of coins were issued from 1878 through 1904 an for the last time in 1921. Assuming the coin is circulated and has no mintmark current values are $30.00-$45.00 depending on the actual grade of the coin.
1891 is a common date Morgan dollar with values for circulated coins at $17.00-$36.00
There is 24 grams of silver in a 1891 US silver dollar.
Retail is $17.00-$38.00 for circulated coins
Please rephrase question.
Assuming the coin is circulated and has no mintmark, retail value is $18.00-$38.00
Current retail value is $17.00-$38.00 for circulated coins depending on grade
A 1891 U.S. silver dollar is a Morgan dollar. This series of coins were issued from 1878 through 1904 an for the last time in 1921. Assuming the coin is circulated and has no mintmark current values are $30.00-$45.00 depending on the actual grade of the coin.
Assuming the coin is circulated and has no mintmark, the 1891 Morgan dollar is a slightly better date Morgan with retail value of $38.00-$45.00 depending on the actual grade of the coin.
1891 is a common date Morgan dollar with values for circulated coins at $17.00-$36.00
In the search box on your home page, type in 1891 silver dollar then click on images, this will bring up a lot of pictures.
It really depends on which coin it is. Is it a US silver dollar or dime? There is a big difference. Is it a world coin? What country is it from? All of these things matter when figuring the value of a coin.
The coin is very common, circulated examples sell for $17.00-$38.00
The 1891 Morgan Silver Dollar can be seen by using the link to a picture of this coin.