Your coin should have a picture of former Chancellor Paul von Hindenburg on it. Its value depends on its condition and mint mark:
Depending on the cost of silver, it is usually $5 to $10 above spot
what is the value of the German mark coin with horse on back dated 1923
Please post a new, separate question with the coin's date. Without that information it's not possible to estimate a value.
The A mint mark (Berlin) is the most common one for this date. sammler.com, a major German collectibles site, quotes a retail value of at most €0.50 (about 75c) for a coin in average circulated condition.
The letter "F" on the front of the coin is not a mint mark; it's the initial of the coin's designer James Earle Fraser. The mint mark position on all Buffalo (= Indian Head) nickels is located below the words "Five Cents" on the coin's reverse side. Please see the question "What is the value of a 1937 US nickel?" for more information.
You didn't describe the images on the coin, but if it carries a picture of Paul Hindenburg and a Nazi swastika, your coin's value as of 06/2008 is roughly: $8 if it has an A mint mark $10 with a D or J $12 with any other mint mark
The 1937 5 mark is 90% silver. With later year being less down too about 60 percent.
This was a common circulation coin until Germany adopted the euro in 2002. At that time it was worth about US$2.50. If your coin is uncirculated its collector value as of 09/2013 is about US$5.00
You need to know its denomination and mint mark. The best site I know for German coin values is www.sammler.com; however, most of it is in German. If you don't read German, please post a new question here and we'll try to ID your coin.
Cash Value : about half a Euro. A one-mark German coin has a value based on the old exchange rate with the Euro. In 2002, the old Deutschemarks were invalidated as legal tender, but marks were exchangeable at the rate of 1.95583 Marks per Euro, which was set in 1999. So the coin may have more or less value as a collectible than if redeemed for Euros.
It's worth about 12 US dollars. For an old coin they are fairly common.
The German 1 Mark coins from that era were actually made of copper-nickel, and the highest collector's value would be around $4, if it's still in uncirculated condition.
THE 1877 5 MARK GOLD COIN FROM GERMANY WAS MINTED IN QUITE A FEW AREAS WITHIN THE GERMAN TERRITORIES APPROX VALUE OF UNCIRCULATED LUDWIG ll at about 1000 euro