Brown Roll Rim (Paxillus involutus) A deadly poisonous fungus forms ectomycorrhizal relationships with trees, including birch and other broadleaf trees, and prefers acidic soil. It was very common and considered edible until it was realised that the effects are cumulative and realised after time. In 1944, the distinguished German mycologist Julius Schaeffer died after eating a succession of dishes containing brown roll-rim. He is thought to be the only professional mycologist to have died of fun