Bigleaf Periwinkle,  a non-native  species, has been added to the USWildflowers.com database.  Scientific name is Vinca major. This plant also goes by the  common names Large Periwinkle, Greater Periwinkle, and Myrtle.  Some folks consider it to be invasive, so use caution in propagating this plant.

Bigleaf Periwinkle - Vinca major