If you found it in change it doesn't really have any collector's value so its only a nickel.
In uncirculated condition, as of 02/2015 it could retail for anywhere from a quarter in the lowest collectible grade (MS60) to several hundred dollars in top condition (MS66 or higher) so it may be worth having it evaluated by a dealer or appraiser.
Note that there are no mint marks on any US Coins dated 1965 through 1967.
August 19, 2009: If you got it in change spend it, the coins are not silver or rare. In 1966, 3 US mints were producing coins but none of them were putting mint marks on their coins. Therefore there is no way to know where a particular coin was made. This nickel can still be found in circulation and thus its circulated value is 5 cents. The uncirculated values are shown in the following list:
Uncirculated Grades........
MS60................................$0.20
MS63................................$0.35
MS64................................$1.80
MS65................................$15
MS66................................$125
MS67................................$1,060
25 cents, all circulation quarters from 1965 to date are made of copper-nickel,
10 cents.
Unless it is uncirculated, it's pocket change.
10 cents unless in a mint set. It is in common circulation and made out of copper-nickel and contains no premium over face value.
1966 (US) dimes are not silver but are copper-nickel and commonly come up in circulation. Unless it is in a mint set, it is only worth 10 cents. Even uncirculated examples outside of mint sets carry little to no premium and little collector demand.
5 cents
Australia has never produced a "nickel" coin.
It's the usual practice of this site to answer a single question at a time. Please see:"What is the value of a 1940 US nickel?""What is the value of a 1942 US nickel?""What is the value of a 1944 US nickel?"
50-500 usd
This design is called either a buffalo nickel or an Indian head nickel; both names are about equally common. Please see the question "What is the value of a 1919 US nickel?" for more information.
It's a very common coin that's still in found in circulation and only face value.
The US nickel was first issued in 1866. Please double-check your coin.
5 cents.
Well... it depends on who wrote the letter. For example, if I had written the letter in 1966.. it wouldn't be worth a plugged nickel!
A 1957 nickel is worth face value only, unless it's uncirculated or a proof coin.
In average condition, both coins are only worth their face value.
Average current retail value is $5.00