Green Clay was born at White Hall on 11 August 1871 and was named Guy Ephrium Herrick. He was the son of John Frank and Mary Clay Herrick. Mary Clay was the oldest daughter of Cassius M. Clay, the "Lion of White Hall." When his parents divorced his mother began calling him Green Clay and at her insistence he changed his name to Green Clay after he reached 21.

Green attended school in Richmond and high school in Ann Arbor, Michigan. He was a student at the University of Michigan for two years, Central University for two years, and graduated from Columbia College in Washington, DC with the LL.B. degree in 1893. He practiced law in Richmond and Cincinnati.

He began working in the newspaper business sometime after 1900 and worked for papers in Ohio, New York, Richmond and Tennessee. He also wrote numerous articles and pamphlets about the history of Richmond and Madison County and worked for the WPA supervising the indexing of court records. He also worked as city clerk, purchasing agent and auditor of Richmond.

He was a member of the Richmond Lodge of Elks and moved to the Elks National Home in Bedford, Virginia in 1947. He died there without descendants on 10 Jan 1962 and was buried on the grounds.