Tricholoma caligatum
INDIANA MUSHROOMS  
Found late summer into fall. Young specimens will have a partial veil that
covers and protects the gills; this will fall away and leave a large, frill-edged
ring on the stem. The stem is white above the ring and brown with scales
below. A similar species,
Tricholoma magnivelare, grows under conifers.
See Tricholoma caligatum
at MushroomExpert.Com
Brown caps can be up to 13cm (5 inches) across, with
a fibrous, scale-like appearance; large ring on stem;
very bitter taste; grows with oak trees nearby.