Look on the back of the coin to see if there's a small mint mark letter below the eagle. It may be blank or there may be an O or S.
Numismedia lists the following approximate retail values as of 06/2011:
No mint mark (Philadelphia):
Very worn condition - $17
Moderately worn - $37
Slightly worn - $110
Almost no wear - $356
Uncirculated - $480 to $30,550 depending on quality
"O" mint mark (New Orleans):
Very worn - $23
Moderately worn - $79
Slightly worn - $162
Almost no wear - $445
Uncirculated - $660 to $20,150
"S" mint mark (San Francisco):
Very worn - $22
Moderately worn - $84
Slightly worn - $138
Almost no wear - $426
Uncirculated - $700 to $15,930
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.
Assuming the coin is circulated and has no mintmark, the 1899 Barber half is a common date coin. For an accurate assessment of value the coin needs to be seen and graded. Most coins show heavy wear. In general retail values for low grade coins are $18.00-$55.00, better grade are $100.00-$250.00 and coins showing almost no wear run from $300.00-$475.00. Values are a market average and only for coins in collectible condition, coins that are bent, corroded, scratched, used as jewelery or have been cleaned have far less value if any to a collector or dealer.
50$
The bill that most closely fits that description is an 1899 US 1 dollar "black eagle" bill. Please see the question "What is the value of an 1899 US 1 dollar silver certificate?" for more information.
Despite its 1899 series date, White's signature means your bill was printed at some point in the 1920s. Please see the question "What is the value of an 1899 US 1 dollar silver certificate?" for more information.
Value is for the silver about $2.50
The US didn't strike any half dollars in 1804.
There were no series letters on 1899 $2 silver certificates. Please see the question "What is the value of an 1899 US 2 dollar silver certificate" for values and other information.
No US One Dollar coins dated 1899 with a legend of "Thirteen Colonies" exist. It's not a US Mint coin.
50$
The US did not print any two dollar silver certificates after 1899.
A US half dollar with a date of 1979 is a Kennedy half dollar not a liberty half dollar. The coin has no silver and is only face value.
The bill that most closely fits that description is an 1899 US 1 dollar "black eagle" bill. Please see the question "What is the value of an 1899 US 1 dollar silver certificate?" for more information.
Despite its 1899 series date, White's signature means your bill was printed at some point in the 1920s. Please see the question "What is the value of an 1899 US 1 dollar silver certificate?" for more information.
It has a metal value of about $10.
Value is for the silver about $2.50
About $4-5
50 cents.
a half dollar