Pyramid Builder Lepidella 
Questionable Stropharia 
Radulomyces confluens 
Radulomyces copelandii 
Radulomyces paumanokensis 
Ramariopsis pulchella 
Red Edge Brittlestem 
Red-banded Cortinarius 
Reddening Lepiota 
Redlead Roundhead 
Redleg toughshank 
Resinomycena rhododendri 
Resupinatus alboniger 
Rhodophana nitellina 
Ringless Honey Mushroom 
Ringless Panther 
Roosevelt Ringless Amanita 
Rose-Tinted Amanita 
Rosy bonnet 
Rosy parachute 
Rosy-gill fairy helmet 
Ruby bonnet 
Ruby bonnet 
Russula-like Amanita