Pleurotus opuntiae
Pleurotus opuntiae is a species of Agaricales fungus that grows in the semi-arid climate of central Mexico and in New Zealand, whose mushroom is edible and considered a delicacy in the cuisine of indigenous peoples of Mexico. It is known as hongo de maguey común in Mexican Spanish, seta de chumbera/nopal in Peninsular Spanish, and kjoo'wada in Otomi language. Phylogenetic research has shown that while it belongs to P. djamor-cornucopiae clade, it forms its own intersterility group, but it has also been claimed to be genetically inter-incompatible with P. australis, P. ostreatus (extra-limital), P. pulmonarius and P. purpureo-olivaceus of New Zealand. Description 
P. opuntiae fruits gregariously in groups of several specimens on dead remains of the plant , from which the binomial name of the fungus derives. They are beige or cream in color. Its gills are very decurrent and its cap, from  in diameter, is quite flat and funnel-shaped, slightly rolled at the edges. It has either a very short stipe, or often basically nonexistent one. References 

Edible fungi
Pleurotaceae
Fungal tree pathogens and diseases