Oak Bracket
Oak Curtain Crust
Oak Mazegill
Oak Pin
Oak Woodwax
Oakbug Milkcap
Oakleaf Cup
Ochre Aldercap
Ochre Brittlegill
Ochre Cushion
Ochrocladosporium elatum
Octaviania asterosperma
Octospora coccinea
Octospora humosa
Octospora rubens
Octospora rustica
Odontia papillosa
Oidiodendron tenuissimum
Oidium chrysanthemi
Oilslick Brittlegill
Oily Waxcap
Oligonema schweinitzii
Oligoporus caesius
Oligoporus fragilis
Oligoporus stipticus
Oligoporus subcaesius
Oligoporus tephroleucus
Olive Brittlegill
Olive Brownie
Olive Earthtongue
Olive Oysterling
Ombrophila violacea
Omphalia bisphaerigera
Omphalia sphagnicola
Omphalina abiegna
Omphalina ericetorum
Omphalina galericolor var. lilacinicolor
Omphalina hudsoniana
Omphalina obscurata
Omphalina oniscus
Omphalina pyxidata
Omphalina rickenii
Omphalina sphagnicola
Omphalina velutipes
Omphalina wynniae
Onygena corvina
Onygena equina
Oospora pustulans
Opegrapha atra
Opegrapha corticola
Opegrapha herbarum
Opegrapha multipuncta
Opegrapha niveoatra
Opegrapha ochrocheila
Opegrapha sorediifera
Opegrapha varia
Opegrapha vermicellifera
Opegrapha vulgata
Opegrapha xerica
Ophiostoma minus
Orange Birch Bolete
Orange Bonnet
Orange Cup
Orange Grisette
Orange Milkcap
Orange Mosscap
Orange Oak Bolete
Orange Peel Fungus
Orange Waxcap
Orbilia alnea
Orbilia auricolor
Orbilia comma
Orbilia curvatispora
Orbilia cyathea
Orbilia delicatula
Orbilia euonymi
Orbilia inflatula
Orbilia luteorubella
Orbilia sarraziniana
Orbilia vinosa
Orbilia xanthostigma
Otidea alutacea
Otidea bufonia
Otidea cochleata
Otidea grandis
Otidea leporina
Otidea onotica
Otidea umbrina
Otthia spiraeae
Oudemansiella longipes
Oudemansiella mucida
Oudemansiella radicata
Ovularia decipiens
Ovularia deusta
Ovularia primulana
Ovularia sphaeroidea
Oxyporus populinus
Oyster Mushroom
Oyster Rollrim