Spiderwort (Tradescantia sp)
(probably Tradescantia ernestiana)
Spiderwort is a native herbaceous perennial common to the central US. It prefers full to partial shade with medium to wet soil and is often found growing at the edges of woodlands. There are several different species of spiderwort and these can be difficult to distinguish without either a lot more experience than Jo and I or side by side comparisons.
Sources and additional information:
Missouri Botanical Garden (Kemper Center)