You really know yur stuff. Are nettles found in the South? Do you just eat the leaves? How can one eat something that is so toxic to the skin?
Here’s the USDA page on Uritca dioica (stinging nettle). http://plants.usda.gov/java/profile?symbol=URDI Looks like it’s found everywhere except Arkansas.
The sting in Nettles if from formic acid. The same thing that makes an ant bite sting. Heat destroys the formic acid.