Hypomyces chrysospermus is a parasitic ascomycete that infects particular species in the Boletales including boletes, leccinums, Paxillus and Rhizopogon. It passes through color changes starting out white and ending up a bright egg-yoke yellow. Inedible.

Hypomyces chrysospermus on boletes

Hypomyces chrysospermus on boletes