This thread will offer a place to list local and state geocaching organizations in the South Atlantic area:
Delaware, Maryland, District of Columbia, Virginia, West Virginia, North Carolina, South Carolina, Georgia, and Florida.
All images below should be links to the referenced site. At this point, I have listed all the groups I could find. If you know of any others, please let me know.
And be sure to check out the "Other Areas"
forum for a list of global organizations too!