The fastest place is a coin dealer. You could also sell it online such as on Ebay, but, you better take some REALLY nice photos of it to show detail. I would also advise that you look up the value in advance.
If you sell to a dealer, expect about 20%-50% of book value. Many coins are so worn that they are not worth much over the weight of the silver. Most amateurs will over-value the coin as they don't understand how to rate it properly to get the value.
A 1880-S Morgan Silver Dollar that is in a mint state of MS67 is worth: $ 450.00.
In MS60 Grade uncirculated, a 1880 S Morgan Silver Dollar is worth about $52. In MS65 Brilliant Uncirculated, it is worth over $330.
Currently a 1880 S Morgan silver dollar in MS65 uncirculated condition is worth $156.
1880 is a common date Morgan dollar, circulated examples are $17.00-$26.00 depending on grade.
If you mean a 1880 Carson City Morgan dollar? circulated examples run from $100.00-$300.00
Yes.
Try eBay.
Currently as of April 2012 a 1880 Morgan silver dollar in MS63 uncirculated condition is worth around 63 dollars.
7-31-11>> Assuming the coin is circulated and has no mintmark, the 1880 Morgan dollar is very common. Values are $38.00 in the grade of VG-8
The 1880 Morgan is also very very common. A circulated example is $38.00 to $44.00 depending on the actual grade of the coin.
$27 to $1300 depending upon the condition of the coin.
Your coin is called a Morgan dollar. "American Eagle" coins are modern bullion pieces made since 1986 for collectors and investors; Morgan, Peace, and other standard-issue silver dollars were made for use in ordinary commerce. They were discontinued in 1935. Please see the question "What is the value of an 1880 US silver dollar?" for more information.