Information from the GM Heritage Center:
This early custom job, mounted in late 1905 on the single-cylinder chassis for 1906, was commissioned from Seavers and Erdman, coach builders in Detroit, for the personal use of Henry M. Leland, founder of the Cadillac Automobile Company in 1902. It was designed to his own exacting specifications and named "Osceola", after a respected chief of the Seminole native American people. The little enclosed 2-seater coupe was top-heavy (it was 5" taller than it was long) and Leland, who drove his cars as hard as he did his employees, is known to have occasionally flipped Osceola on its side, at speed. Originally painted green, it was later repainted dark blue; Osceola is/was on display in the Historical Collection of GM's Cadillac Motor Car Division.
(The coachbuilder involved was actually named "Sievers and Erdman". Many web sites spell it as shown in the quote from GM.)
A missing image:
