What is Yellow Dock?
Yellow dock also known as Curled Dock, Curly Dock, Yellow Dock, Sour Dock, or Narrow Dock is a perennial flowering plant in the family Polygonaceae, native to Europe and Western Asia. 
It can be used as a wild leaf vegetable; the young leaves should be boiled in several changes of water to remove as much of the oxalic acid in the leaves as possible, or can be added directly to salads in moderate amounts. 
The roots have also been used medicinally as an astringent, tonic, and laxative. Compounds contained in the plant's roots have been clinically verified to bind with heavy metals such as lead and arsenic and expel them from the body by stimulating biliary function in the liver. The plant is considered a highly effective blood cleanser and is used by herbalists to assist the body in eliminating heavy metals and to treat other hepatic disorders.