A Quarter Not Worth 25 cents?

Okay today I was getting ready to go to the gas station and get a snack with my girlfriend when I grabbed my change off my desk, some quarters, dimes and nickels, and then I realized one quarter didn't look right. It had smooth edges. I recently took a class and my professor enjoyed giving us useless facts throughout the class and one of them was that before 1964, quarters we made out of 90% silver, which back in that time, silver was worth more money than what a quarter was worth. People would shave their quarters down and get more money for the shavings because pure silver was worth a good price. Once the Mint found this out they took action and tried to solve this problem. After 1965 the quarter was composed of copper and nickel, which some may know that those two materials are not worth very much. So the rigid edges added to the quarters were put into place and that way the banks would know if someone tried to shave the quarter or not because there would be smooth edges, like the 1966 quarter I have. To bad because the 1966 quarter had no silver in it at all.

I have found a website that interested me and help me come to my conclusion I have mentioned above.

http://www.coinfacts.com/quarter_dollars/washington_quarter_dollars/1966_quarter_dollar.htm

I have found this information to be very interesting...
When the Coinage Act of 1965 was passed, it became mandatory that the Mint continue to use the 1964 date on all 90 percent silver coins (half-dollar coins, quarter-dollar coins, and 10-cent coins). Therefore, all of the 90 percent silver coins that the Mint manufactured in 1964, 1965, and 1966 bears the date 1964. The last of the 90 percent silver quarter-dollar coins was struck in January 1966

Maybe my 1966 quarter is originally silver but stamped 1966 instead of '64.