Poole was educated at home until he was almost 7 years old, at which time he was enrolled in Chicago's University School for Boys. There he first showed a proclivity for the written word, working briefly on the staff of the school newspaper. His was a privileged youth, spending summers at the family's seasonal home at Lake Forest, on the shores of Lake Michigan. The family's Michigan Avenue home in Chicago was populated with servants, including gardeners and governesses, and he grew up in proximity of the scions of the city elite, including young relatives of Cyrus McCormick and Abraham Lincoln.