Old Silver

On a snowy winter day, I was checking my mail box at the post office. A little girl was trying to buy stamps from a vending machine, putting coins in one by one. 

She was having trouble. One of the coins kept getting rejected. She retrieved it and put it through the machine several times -- same result. The vending machine refused to accept it. 

Finally, she asked me: "Do you have a quarter? The machine won't take this one."

She handed me the coin. I immediately saw that it was a pre-1964 quarter. I gave her old quarter back to her and told her to hang on to it. "It's got silver in it," I told her. Then I gave her a shiny new one. The machine took it.  

Good deed done, I trudged off into the snow with my mail.