Anecdotal Evidence

Here's a charming story supporting my hypothesis that what is on the ground outside is not food.

So my daughter crawled by, stopped and looked at me with an expectant look on her face. The look that usually means "You usually clean me when I get like this". I glanced, then looked more closely. My first thought was "How did you get hold of an Oreo cookie - wait do we have Oreos??"
That's when I realized she had actually eaten a clod of mud off one of our shoes and her mouth was full of dirt; leaking dirt. She smacked her gums together over and over, moving her tongue like she was trying to get rid of the tiny grains. Her expression said "this is not delicious."
I bet it's not.

And this is why we put the shoes away and don't let her near them.