Carex woodii
A plant IDed by Kevin Tungesvick. He said it is rarely seen with flowers, though it had some when I saw it.
Plant habit at Mounds State Park, 6/6/04.
An inflorescence at Mounds State Park, 6/6/04. Note distal staminate and proximal pistillate portions.
Closer view of the pistillate portion of the inflorescence at Mounds State Park, 6/6/04.