The U.S. has never used an "E" mint mark. The mints that struck Morgan dollars were Philadelphia (no mark), D = Denver, S = San Francisco, O = New Orleans, and CC = Carson City.
Please look under the eagle's tail feathers again, and refer to this page for a price guide.
The mint mark (if it has one) on all Morgan (1878-1904 & 1921) silver dollars is on the reverse of the coin, just above the letters "DO" in dollar.
About $27.
About $150.
42cents
"DO" isn't a mint mark. The mint mark on a silver dollar for that year is on the reverse (tails) side, just above the letters "do" in the word "dollar."
One Dollar
about $25 depending on condition and mint mark
If the coin has any wear the value is for the silver, about $8.50
They are still found in circulation, have no silver and are only face value
A Morgan dollar without a mint mark would have been minted in Philadelphia. The P mint mark wasn't used on $1 coins until 1979. But more information is needed to determine a value. Morgan dollars were minted from 1878 to 1904 and again in 1921 so you need to know the coin's date, plus have an idea of how worn it is. Please post a brand-new question with the coin's date, or enter the question "What is the value of a [date] US silver dollar?" in the box at the top of the page. [date] is of course your coin's specific year.
$15 to $20 depending on condition and variety.
Post new question with The Mintmark please.