Interesting find. If your coin is in fact an error, it would be a "wrong planchet error." From the pictures it appears it would have been a "quarter struck on dime planchet" error more specifically. Here is a quick test for you: Is the coin the same thickness as a dime? A dime is 1.35mm and a quarter is 1.75mm. Now it may be thinner than the dime, but if it is over say 1.40mm I would say no chance it is real. The other thing is, I doubt that the entire edge would be reeded if its real. The reeded edge is obtained during the striking process. The collar in which the coin is struck contains grooves that, once the die applies pressure to the planchet, leave the reeded edge. Now, if you imagine a dime in a quarter-sized collar, I doubt that all of the reeds would imprint 360 degrees around the entire planchet. Let us know what you find. If it's the same thickness as a quarter, it's more than likely not a real error. If in doubt at all though, take it to an expert. Without holding and seeing the coin personally, it's very difficult to ascertain much.