The Imperial Cornet Band of Oz
From the 1908 young adult novel Dorothy and the Wizard in Oz by L. Frank Baum. Based in the Emerald City, they play at occasions of state, such as the grand parade at the end of the novel.
Not to be confused with The Royal Court Band of Oz mentioned a couple pages later.
The procession was very imposing. First came the Imperial Cornet Band of Oz, dressed in emerald velvet uniforms with slashes of pea-green satin and buttons of immense cut emeralds. They played the National air called "The Oz Spangled Banner," and behind them were the standard bearers with the Royal flag. This flag was divided into four quarters, one being colored sky-blue, another pink, a third lavender and a fourth white. In the center was a large emerald-green star, and all over the four quarters were sewn spangles that glittered beautifully in the sunshine. The colors represented the four countries of Oz, and the green star the Emerald City.