Do you mean that the coin does not have the normal reverse you are used to seeing? If so its not and error. Cents were minted with a reverse that had two stalks of wheat up until 1959. If you believe the coin has some type of error beyond that that you have to provide us pictures or a description of what the coin looks like.
You were wrong. Saying that they were minted up til '59 implies that there are wheaties out there dated 1959. The were minted up til '58 would have been correct.
Not any error. It has either been buried or exposed to acid. What you are seeing it the resultant corrosion.
Hey Rick.. Its plausible that there was a 1959 Wheat Cent minted. HERE It would be called a mule.. Also I read it just as the person typing it meant it to be. One thing I do know.. make sure you run spell check here or some "perfectionist" will jump on you. To, Two, Too....