The term you are looking for is "NO DROP" that is usually a beginner ride at a 12mph pace. Also check with local advocacy groups. Looks like a good place to start would be the "Mephis Hightailers".
Looks like they have several rides weekely.
http://memphishightailers.clubexpres...module_id=8735

More info for your area

http://www.google.com/search?client=...=Google+Search