no your brain and nose are safe from mushroom or fungus growth.
handled old cooking mushrooms too old to use picked nose with mushroom secretion on finger can mold grow in nose/brain. i was looking for ingredients for dinner and found old mushrooms i inspected them to see if they were good they were not while throwing them out i also picked my nose with the wierd slimy stuff from mushroom on my finger didnt think of it at the time but now im worried that the secretion off the mushroom could cause fungus to grow inside my nasal cavity or brain is there a possibility of this?