This is a gorgeous hand-painted watercolor textile design, mounted to black rag paper, by William Palmer, c. late 1920s, likely done when he was in school. Very Art Deco, with a strong Cubist influence as well; I'd like to think the repeating fragment of a guitar is an homage to Picasso!
Palmer (1906-1987) was born in Des Moines, studied at the Art Students League in NYC under Thomas Hart Benton among others, and studied fresco painting at the Ecole des Beaux-Arts in France--later painting a series of WPA funded murals in the U.S. Said to have made a sketch a day at least, examples of his far-ranging work (drawings, paintings, prints, illustrations including for several children's books) are held in the collections of the Whitney Museum, Cranbrook Academy, the National Gallery, the Metropolitan Museum, the White House, among many others, and his archive is housed at Hamilton College.
Paper size is 8 1/8" x 9 5/8"; painting measures 4"x5 1/2. Very good condition, still very bright and crisp.