Well all things considered, that sounds fitting. My Grands put them at my Mom's grave because she was always finding them in some parking lot, dirt, whatever and we had to pick them up for her. I once told her I didn't like Lincoln enough to bother but then said "yes Maam". I knew better when she got 'that look' in her eyes.
There's the paying for the crossing theory, the good luck in passing over theory and the 'whatever' in case one of them is right theory. Can't hurt to leave a penny. Can't buy anything with just one.