(Fries) P.D. Orton
Gymnopilus junonius, also known as Gymnopilus spectabilis, Laughing gym or Laughing Jim, is a large and very widely distributed hallucinogenic mushroom which grows in dense clusters on dead hardwoods and conifers. It has a rusty orange spore print, a bitter taste, stains red with KOH and turns green when cooked in a pan.
Gymnopilus junonius includes subspecies which contain the hallucinogen psilocybin. Specimens found in the eastern US or Japan is more likely to contain psilocybin than similar mushrooms found in the western part of the US or Europe.  In Japan this mushroom is called waraitake, which translates to "laughing mushroom". This mushroom is often mistaken for Gymnopilus ventricosus, which contains no psilocybin.
The cap ranges from 7 to 42 cm across, is convex, and is bright orange, orangish brown, or reddish brown with a dry scaly surface. The flesh is yellow and the gills are adnate to subdecurrent. The stem is 25-265 mm long, .8 to 9 mm thick, dusted with rusty orange spores and often narrowing near the base.
This mushroom grows just about everywhere that decaying wood can be found.
- G. M. Hatfield, L. R. Brady (1969). "Occurrence of bis-noryangonin in Gymnopilus spectabilis". Journal of Pharmaceutical Sciences. 58 (10): 1298–1299. Unknown parameter
- Gastón Guzmán, John W. Allen & Jochen Gartz, A Worldwide Geographical Distribution of the Neurotropic Fungi, An Analysis and Discussion, Ann. Mus. civ. Rovereto Sez.: Arch., St., Sc. nat. Vol. 14 (1998) 189-280 2000
- C.J. Alexopolous, Charles W. Mims, M. Blackwell et al., Introductory Mycology, 4th ed. (John Wiley and Sons, Hoboken NJ, 2004) ISBN 0-471-52229-5
- Tom's Fungi of the Month - Gymnopilus spectabilis
- Mushroom Expert - Gymnopilus junionius
- Mycologica - Scientific Gymnopilus information