Hi Lisa, I have 3 candidates (Genus) for your mystery fungus:TRAMETES, STEREUM
or TRICHAPTUM. I think all are found on dead wood. Compare descriptions. Hope
it is one of these.

Rich Hyerczyk


TRAMETES....UNDER SIDE WHITISH WITH PORES
Trametes versicolor, formerly known as Coriolus versicolor and Polyporus
versicolor, is a common polypore mushroom of the genus Trametes.
The top surface of the cap shows typical concentric zones of different colours.
Flesh 1-3 mm thick, leathery texture. Cap with rust-brown or darker brown,
sometimes blackish zones, Older specimens can have zones green algae growing on
them, thus appearing green. Commonly grows in tiled layers. Cap flat, up to 8 x
5 x 0,5-1 centimeters, often triangular or round, with zones of fine hairs. Pore
surface whitish to light brown, pores round and with age twisted and
labyrinthine. 2-5 pores per millimeter


STEREUM.... UNDER SIDE SMOOTH
Stereum species are wood decay fungi that do not have tubes. They are simply
small bracket-shaped membranes appearing on dead wood. The underside of the
membrane contains spores but no ornament, i.e. gills, of any kind.


TRICHAPTUM...UNDERSIDE VIOLET COLORED & PORED
Trichaptum biforme
Ecology: Saprobic; growing in overlapping clusters on hardwood logs and stumps;
late spring, summer and fall; found in all 50 of the United States and all the
Canadian provinces; in eastern North America it is one of the most commonly
encountered fungi. Trichaptum biforme is a voracious decomposer of dead wood. It
causes a straw colored sapwood rot in standing trees.
Fruiting Body: Up to 6 cm across and 3 mm thick; more or less semicircular,
irregularly bracket-shaped, or kidney-shaped; flattened-convex; hairy, finely
hairy or fairly smooth; with zones of whitish to grayish white colors; the
margin sometimes pale lilac; without a stem.
Pore Surface: Purple to lilac, with the strongest shades near the margin; fading
to buff or brownish in age; with 3-5 angular pores per mm; usually eroding and
developing spines or teeth with maturity; not bruising.
Flesh: Whitish; tough and leathery.
Chemical Reactions: KOH negative to pale yellowish on flesh and cap surface.
Spore Print: White.