I don’t know if this would constitute an error, but I’m curious to get some opinions. Obverse and Reverse appear to be perfectly normal, but when you look at the edge the copper is gone and it looks like a silver. It weighs the same as a common quarter. What could change the edge of a quarter without affecting the weight?
You've probably seen the advertising and sales of coins on the home shopping networks. For a while, they were selling plated coinage (sometimes you'll find 'gold' plated quarters/nickels CRH) to buyers that liked a certain look. Folks lost their interest, or the owner passed on, and the coins became liberated 'spenders'. That's what probably happened here.