In traditional medicine, Poria mushroom filaments have been used for loss of memory (amnesia), anxiety, restlessness, fatigue, tension, nervousness, dizziness, urination problems, fluid retention, sleep problems (insomnia), an enlarged spleen, stomach problems, diarrhea, tumors, and to control coughing. https://www.webmd.com/vitamins/ai/ingredientmono-246/poria-mushroom

From the manufacturer: 

This product is the white part of the sclerotia of the Poriaceae plant Poria cocos with natural pine roots (that is, Poria).  Poria cocos are the sclerotium of Poria cocos Schw. Wolf, a plant belonging to the family Polyporaceae, Poria cocos Schw. The original species is a lower plant, a fungus that is parasitic on pine trees. The medicinal part is dried sclerotium. The taste is sweet and it is mild in nature.