All real US gold coins have dates but not all have a mintmarks
Please post a new question with the coins' dates and mint marks.
Mint marks are on the back of the coins, it's under the wreath on $1 coins and the eagle on $2.50 & $5.00 coins.
Australian coins minted at the Melbourne Mint do not have a mintmark.
Assuming the coin is circulated and has no mint marks, retail value is $1,330.00-$1,500.00 NOTE: $20.00 gold coins are double eagles $10.00 coins are eagles.
The San Francisco mint opened in 1854 and produced coins almost every year to the present except for a short time from 1955 to 1967. The facility at West Point began striking Lincoln Cents in 1974 and continued until 1986, but no mint mark was place on any of the coins. In 1983 the "W" mint mark appeared on gold commemorative coins. In 1986 American Gold Eagle coin were produced but did not bear a mint mark. Today the "W" mint mark appears on all gold commemorative coins and a few silver coins as well.
The 1928 Saint-Gaudens double eagle was only struck at the Philadelphia Mint so no coins bear a mint mark. But for coins of this series that do have mint marks it's just above the date. All so the 1928 double eagle is the highest mintage (8,816,000) of any US gold coin of any type.
So far just a few error coins missing the dates from the edge of the coins and the Proof and Uncirculated coins sold from the Mint have slightly higher values.Also I hope you know the coins are brass not gold.
The gold colored Sacajawea dollars are worth a dollar. All current U.S. $1 coins are not gold, they're gold-colored. The metal is a manganese-brass alloy. They're worth $1 each, regardless of the design. Feel free to spend them as billions have been struck.OTOH $1 gold coins issued in the 1800s were real gold and are worth considerably more than $1, but you need to know their dates and mint marks.
All Presidential Dollars have their dates and mint marks on the coins' edge. Those with a portrait of Zachary Taylor were minted in 2009. Remember that they're brass, not gold, and only worth $1.
If your coin does not have a mint mark then it means it was minted at the Philadelphia mint. These coins are usually not as rare. However recently P mint marks were added to coins to indicate that they were made at the Philadelphia mint.
No mint mark coins are produced at the Philadelphia,PA
The current US mint marks are:P for PhiladelphiaD for DenverS for San Francisco (for proof coins only)W for West Point (for commemoratives and gold only)Until recently most coins from Philadelphia did not have a mintmark so you may find many older coins lacking mint marks. Dates for the P mint mark are:> 1942-45 : "war nickels"> 1979-present : dollars> 1980-present : nickels, quarters, dimes, halvesPhiladelphia cents do not have a mint mark, even after 1980.Mint Marks on Older CoinsS for San Francisco on circulating coins 1854-1955, also some nickels and cents 1968-74 C for Charlotte, NC 1838-1861CC for Carson City, NV 1870-1893D for Dahlonega, GA 1838-1861O for New Orleans, LA 1838-1861 and 1879-1909