The NM, Mycophile, is in Carpenter's Landing. You must trade a Danceshroom, Sleepshroom, and Woozyshroom to the ??? at I-11 to pop it. Current drop record is approximately 40%.
Best way to get here is NOT via ferry, but just OP Warp to Jugnar Forrest, and go directly east, zone into Carpenter's Landing and you are right at the ???. Also bring several danceshrooms. There are Shriekers there (Funguar), but they only drop woozyshrooms and sleepshrooms. You will need one of each to pop the NM. The respawn time is 15 minutes. You do not need to zone for the ??? to reappear.