1938 buffalo nickels were only minted at Denver. The "D" is on the back under the words FIVE CENTS. The F on the front of the coin is the designer's monogram and not a mint mark.
Numismedia lists the following approximate retail values as of 04/2012:
"D" mint mark (Denver):
Very worn condition - $3
Moderately worn - $3
Slightly worn - $4
Almost no wear - $9
Uncirculated - $19 to $7,500 depending on quality
There is also a variety with a shadow "S" under the D mint mark on the reverse side. These are comparatively scarce and are worth 2 to 3 times those with a clear D.
The reason for the D over S mint mark is that there were delays in introducing the new Jefferson design at the start of 1938. To meet demand for nickels the Mint authorized production of another year of Indian Head nickels at Denver and San Francisco while Philadelphia geared up for the new designs. Things went better than expected in Philadelphia so San Francisco didn't need to mint any Indian head nickels. To save money the "S" mint dies were recycled for use in Denver but not all of the mint marks were completely removed.
DISCLAIMER: The retail values quoted are the best available as of the date shown, but may vary due to market fluctuations. 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.
The 1938-D Buffalo NICKEL is a common coin, in average condition values are $1.00-$3.00.
The last buffalo nickels were made in 1938.
Buffalo nickels were minted from 1913 to 1938
The last Buffalo nickel was struck in 1938.
Buffalo nickels were minted 1913-1938.
It's Indian Head or Buffalo nickel not Buffalo Head, values are $1.00-$3.00 for average coins
The last buffalo nickels were made in 1938.
Buffalo nickels were minted from 1913 to 1938
Buffalo nickels were minted from 1913 to 1938
The last Buffalo nickel was struck in 1938.
Buffalo nickels were minted 1913-1938.
Buffalo nickels were only struck from 1913 to 1938.
It's Indian Head or Buffalo nickel not Buffalo Head, values are $1.00-$3.00 for average coins
There is no such thing as an 1889 Buffalo Nickel. Buffalo nickels were only minted from 1913 to 1938. A nickel minted in 1889 would be a Liberty Head or "V" nickel.
Please check again and post a new question. Buffalo nickels were struck from 1913 to 1938. Any nickel dated 1939 would be a familiar Jefferson nickel. Look at the coin again, 1938 was the last year a Buffalo nickel was made.
Check that date again, because the last year for buffalo nickels was 1938.
Please check again and post a new question. Buffalo nickels were struck from 1913 to 1938. Any nickel dated 1943 would be a familiar Jefferson nickel.
Please check your coin again and post a new, separate question. Buffalo nickels were struck from 1913 to 1938. An 1878 nickel should be a shield nickel.