Reishi (Ganoderma sessile) is a type of mushroom found on hardwood trees in warm, humid regions. It has a shiny, reddish-brown to dark brown cap with a tough, woody texture. Reishi is known for its bitter taste and has been used in traditional medicine for its potential health benefits, including anti-inflammatory, antioxidant, and immune-boosting properties. It is often used in soups, teas, and other medicinal remedies. However, more research is needed to fully understand its medicinal effects.