A childhood belief about birds

When I was little, I remember time and time again when I would be eating with my Gramma K, and I would drop something on the floor -- she'd pick it right up and eat it. I was in shock at first. She always said, tho, that after all, "We eat over at least a ton of dirt every day, so it doesn't really matter." Well, years later, after eating lots of stuff that had fallen on the ground and remembering her motto, I realized that "over" could mean "over the top of," as in: Under our feet. I didn't eat dropped food as freely after that insight.