They grow it in PA. 
Ustilago maydis is an excellent example of this phenomenon. It's a fungus that grows primarily in sweet corn; infected kernels grow large and oddly shaped, turning grey or black as they fill with spores.
In the US, it's corn smut, a disease to be eradicated. In Mexico, it's huitlacoche (wheat-lah-KOH-chay), a delicacy to be savored. US farmers destroy it or feed it to the pigs. Mesoamerican cultures, such as the Aztec and Maya, prized it. The USDA has spent considerable effort and money to eliminate it. Mexican farmers are filled with joy when they see it, because they know they can sell their crop at a much higher price.
Attitudes are changing in the US. After certain trendy restaurants began to serve huitlacoche, the USDA started an experimental program to allow farmers in Pennsylvania and Florida to cultivate Ustilago maydis. Whether this will be a success remains to be seen.
I have a foot in each camp: both of my parents grew up in Ohio farm families and have vivid memories of shucking smutted corn, the grey spores sticking to their hands. To them, it's a disease. I've also been exposed to the other point of view. I'm left in the odd position of enjoying eating the fungus (it's very tasty in scrambled eggs), but disliking the look of it. In my family, it may take one more generation before it's truly "good to eat".
Note: Looks like somebody beat me to it --------------------------------------------------------------------------------