This is a corn fungus. Instead of throwing it out, I ate it for lunch.

Sitting on my cutting board here in nice little slices is huitlacoche, or corn smut. It's a fungal disease that happens to corn kernels, turning them into giant gray bulbous mushrooms instead of tightly packed rows of yellow kernels. It's not considered a problem so much as an alternate food source to our Mexican neighbors, and they introduced the idea to Americans.
More info about huitlacoche and a scarier-looking photo available at http://www.gourmetsleuth.com/Articles/Mexican-Ingredients-1032/huitlacoche.aspx
I'm sure it's easy to come by here in Illinois corn country, but I've only seen one seller of huitlacoche so far, the person I talked to at the Bloomington Farmer's Market who sold me a little clump for a dollar.

My plan: cut it in slices, saute it and add it with some sauteed zucchini to a quesadilla.

The result: my huitlacoche did not live up to its vaunted reputation for truffle-like smoky goodness. Maybe there wasn't enough, maybe I didn't use the correct method for cooking it, maybe the batch I had was unusually bland, but you know your corn fungus isn't impressive when zucchini has a more pronounced flavor. I found that although there was fungus in every bite of my lunch, it was too subtle for me to notice it most of the time.