What is the value of a 1922 US silver dollar?

These coins are called Peace dollars and were issued to mark the end of WWI. They're made of 90% silver, and contain about 25 gm of that metal. The rest is copper. That means their retail melt value is about 3/4 the price of 1 oz of silver at current market rates. However, some of these coins can be worth more to collectors depending on condition:

Look on the back of the coin to see if there's a small mint mark letter above the Word ONE. It may be blank or there may be a D or S. (The intertwined A and F on the front of the coin are the designer's monogram and not a mint mark.)

Numismedia lists the following approximate retail values as of 05/2011:

No mint mark (Philadelphia):

Very worn condition - $36

Moderately worn - $38

Slightly worn - $38

Almost no wear - $39

Uncirculated - $44 to $8,450 depending on quality

"D" mint mark (Denver):

Very worn - $36

Moderately worn - $38

Slightly worn - $38

Almost no wear - $40

Uncirculated - $47 to $15,150

"S" mint mark (San Francisco):

Very worn - $36

Moderately worn - $38

Slightly worn - $38

Almost no wear - $40

Uncirculated - $47 to $35,750

1922 was the first full year for the famous "Peace" design commemorating the end of WWI. It's also the highest mintage and most common date of the entire series. Because of that 1922 Peace dollars are quite common in many collections.

However a few 1922 Peace dollars were struck in the same high relief as those made in 1921. These are identifiable by their deeper images, but are quite scarce and should be examined by a professional. Values can range from $250-300 for a worn specimen to several thousand for a high-quality uncirculated coin.

In addition there were some matte proof versions struck that can bring over $30,000!

The spelling "TRVST" is NOT an error. During the 1920's it was common for artists to use the Latin alphabet. Latin only has 24 letters and uses "V" where modern languages use a "U"

E Pluribus Unum

The motto E Pluribus Unum (Latin for "Out of Many, One") is on ALL $1 coins minted since 1878 so that's not specific enough to ID any one coin.

Silver Eagles

Silver eagles are bullion coins minted since 1986 for sale to collectors but not for spending. Peace dollars were made for use in ordinary circulation just like dimes and quarters.

DISCLAIMER: The retail values quoted are the best available as of the date shown, but may vary significantly due to changes in the precious metals market. Also the wholesale (buying) price of a coin will be less than the selling (retail) price. A reputable coin dealer will be able to give a more accurate valuation based on inspection of the coin.
1922 is the most common date for Peace dollars, so the value is primarily for the silver content. At present (22 June 2012), it's worth around $21.