British soldier lichen 
Brittle cinder 
Brown Funnel Polypore 
Brown oyster mushroom 
Brown star-footed Amanita 
Brown-eyed Camouflage Lichen 
Brown-toothed Crust Fungus 
Browned Pixie-cup Lichen 
Brownish Conecap 
Brownit 
Bryoperdon acuminatum 
Buellia spuria 
Buellia stillingiana 
Bulbothrix meizospora 
Bulbous bonnet 
Bulbous Honey Fungus 
Bullseye Leaf Spot 
burn site Mycena 
Bushy Beard Lichen 
Butter-foot bolete 
Butterball 
Buttery Collybia 
Butyriboletus querciregius 
Byssocorticium atrovirens