Male. Long antennal appendages that curve inwards and curled up proboscis can be seen in photos 4-6. Deciduous woods, in a vernal pool.
In a fresh water vernal pool
Perigynia mostly longer than 5mm; sheath front reddish-spotted, back of sheath white-septate; leaves strongly glaucous abaxially; ligules long to short, round. Plant forms rhizomatous patch.
Same plant as in this earlier observation: https://www.inaturalist.org/observations/140902083
Certainly laxiflora-type, but rather robust growing in sandy, dry pine/oak uplands, though relatively close to a vernal pond so groundwater is likely not far away.
Measurements upon returning suggestive of striatula, but will require additional information:
Perigynia = ±4.5 mm
Achenes = 3+ mm
Terminal spike = 26 mm
Max leaf width = ±11-12 mm
Probably feeding the nestlings. The Cracked-Cap polypore provides a nice awning over the nest entrance.
Here is another observation of a different cavity under a Cracked Cap Polypore, not far from this one:
https://www.inaturalist.org/observations/148484884