The second COUNTRY CLUB PLAZA structure, known as the Triangle Building, was completed in June 1923. Its initial tenants included Wymore Hardware and a self-service Piggly Wiggly market.
Photo from State Historical Society of Missouri / J.C. Nichols Company Scrapbook

The Piggly Wiggly grocery store chain had its beginnings in Memphis, Tennessee, in September 1916. By the time that this COUNTRY CLUB PLAZA store opened, there were 1,200 locations in twenty-nine states.
Photo from State Historical Society of Missouri / J.C. Nichols Company Scrapbook

Shoppers entered the COUNTRY CLUB PLAZA Piggly Wiggly through the turnstyle seen here and proceeded through the entire store before exiting at a checkout counter. 
Photo from State Historical Society of Missouri / J.C. Nichols Company Scrapbook

The Triangle Building also housed the Hunter Brothers Drug Store.
Photo from State Historical Society of Missouri / J.C. Nichols Company Scrapbook