Please check your coin again and post a new, separate question with the coin's denomination and any other information that might help to ID it. No 1908 regular-circulation coins have a buffalo on them.
The first US nickels were made in 1866. Buffalo nickels were struck from 1913 to 1938. Look at the coin again and post new question.
Check that coin again. The first year for buffalo nickels was 1913.
If its in good condition, find your local hobby or pawn shop to determine the exact value. Such coins can be rare and if possible should be taken to a coin collectors store or a place where they specialize in old money.
Assuming the coin is circulated and has no mintmarks, retail value is $1.00-$4.00 for most coins. The 1930 Buffalo nickel is a very common coin.
Assuming the coin is circulated and has no mintmark, the 1908 Barber dime is a very common coin, for a coin in average circulated condition the values are $2.00-$8.00 retail.
If you mean a $2.50 Gold coin dated 1908 retail values for a circulated coin are $185.00-$250.00 with uncirculated at $350.00+
Current retail value for a certified 1908 Half Eagle is about $5,000.00 in MS-64
A 1934 Buffalo nickel is not a rare coin, retail value for a average circulated coin is $1.00-$5.00
Such a coin was not made by the US mint and therefore has little to no collector value. Most of the value would depend on the metal content or if you sold it to a Buffalo Sabre collector.
Check that coin again. The first year for buffalo nickels was 1913.
You are going to have to be a lot more specific. You need to tell us the denomination of the coin and condition if you want to know the value. All you've told us is you have a British coin from 1908 with Edward VII on it.
No US $1 coins were struck in 1908, look at the coin again and post new question.