You can join by registering online on the Wild Ones National website,  

Wild Ones, Native Plants, Natural Landscapes is a non-profit, educational organization. Your membership is considered a donation and is entirely tax-deductible.

Joining Wild Ones gives you access to the camaraderie and information resources of other native plant enthusiasts. A single membership covers both the national organization and your local chapter. Members receive the Wild Ones New Member Handbook and the Wild Ones Journal, a bimonthly publication. In addition, the Twin Cities Chapter publishes a periodic e-zine, Wild Ones Reflections, and a local quarterly member newsletter.

Membership benefits include participation in any and all Wild Ones chapter activities, either locally or across the United States. These activities include such events as seed gathering, seed exchanges, plant rescues, plant sales, speaker presentations, garden tours, conferences, and bus tours.