It's been argued here that there were '64 SMS, not that I believe it. But there are some here that argue the point, that's the only reason I used that date.
That's okay as you will not likely encounter a SMS coin in circulation that did not get there by mistake. These years also had regular circulating coins which you will find. Sorry guys but I've never heard the story about 64 SMS coins. Maybe these were test coins? If I'm wrong I'll certainly eat crow.
Here (under the pics and all) is some information that may help you determine what to expect if you are looking for a pre-1965 (meaning 1964) SMS coin. http://www.pcgscoinfacts.com/Coin/Detail/4170 You will find that the collection that the known ones came from were believed to be acquired by a person who knew the mint director. It is more likely that these (yours), which show no specialness that I can see on their surface, are regular run-of-the-mill nickels from that date. What you might start doing if you think you stand a chance of finding one in circulation is to buy and study the 1965-67 SMS sets and really look hard at the differences those show to your pre 1965 and your 1968 and on nickels as far as strike and looks to the metal, as the ones known can more be considered a 'pattern' type coin I think (they were not made as part of SMS sets).
@Kasia beat me but here is more info on the sms sets of 64 http://www.pcgs.com/News/1964-Special-Mint-Set-Coins
"It is strongly recommended you purchase coins already graded by PCGS since our experts are well aware of the discernable differences in regular issue mint state or proof coins compared to the special 1964 SMS coins." Hmmmm. makes me wonder if there is a die marker or specific measurable something on this. Makes me think either only one die was used or perhaps they know a proof die was used.... But I could just be barking up the wrong tree on this.
Supposedly the sms sets of 64 have a decernable satin finish to the fields. I've never seen one. But could be just what you're saying as well.
