Michael Smith Coffey was the second son of Athan Coffey and Mary "Polly" McGuire. He went by his middle name.

Smith's siblings were: William Harvey Coffey, Susan Caroline Coffey-Wilson, Josiah Boone Coffey, Mary Emaline Coffey-Byers, Sarah Jane Coffey-Byers, Athen Napoleon Coffey, Hannah Roxanna Coffey-Byers, Nicholas Lee Coffey, and Emma Stuart Coffey-Hooper.

Smith Coffey can be found in the 1850 and 1860 census residing in his hometown of Murphy, Cherokee County, North Carolina. The 1850 census lists him with his parents, Athan and Mary Coffee, and William H. Coffee, Susan C. Coffee, and Josiah B. Coffee.

Smith Coffey fought in the Civil War for Company A, 2nd Regiment, North Carolina Cavalry at the young age of 19. He was hospitalized on April 6, 1863 at Richmond, Virginia for a gunshot wound in the abdomen. He was then transferred on April 23, 1863 to London, Tennessee. He later received a disability discharge on June 5, 1863 in Knoxville, Tennessee. After the Civil War ended, Michael Smith Coffey rode a horse to Texas, where he remained until his death.

Smith was the only one of his family to leave North Carolina at that time. The Coffey's were very rich people, but everything was taken from them by the Yankees (i.e. personal property, servants and slaves, and they were taxed out of their land).

Michael Smith Coffey married Nancy Anastasia Kerby on August 6, 1872 in Gainesville, Coryell County, Texas. Nancy was a cousin to Kit Carson. During the Civil War, Kit Carson fought for the North against Michael Smith Coffey who fought for the South.

After Michael Smith Coffey left Murphy, Cherokee County, North Carolina to fight in the Civil War and then moving to Texas, it was 27 years before he returned to North Carolina, or saw his parents again.

Smith Coffey and Nancy Anastasia Kerby became the parents of Laura Lee Coffey-Shelton, Mary Jane "Molly" Coffey, Boonie Coffey-Bridges, Roxanne "Roxie" Coffey, Cicero Coffey, Dora Coffey-Wright, Sul Ross Coffey, William Harvey Coffey, Samuel Carson Coffey, and John Clifton Coffey.

Around 1899, Smith Coffey moved his family to Tarpley, Bandera County, Texas, where he lived out the remainder of his life.