This is a favrile-glass mosaic called "Garden Landscape and Fountain" by Louis C. Tiffany (1848-1933) that was installed in Tiffany Studios showrooms in New York City ca. 1915. The mosaic is now on exhibit at the American Wing of the Metropolitan Museum of Art.
From the Met exhibit caption:
Tiffany's work in mosaic, inspired by Byzantine examples he had seen abroad, dates to the 1880's, when he began experimenting with iridescent glass and transparent tesserae backed with metal leaf. Mosaic decoration graced countless interior by him, from churches to department stores. The culmination of his interest was the vast "Dream Garden" mosaic, created in 1925, after designs by Maxfield Parrish, for Edward Bok at the Curtis Publishing Company in Philadelphia. Tiffany may have made this shimmering garden landscape as a preliminary study for the Curtis commission. It was among the decorations that graced the Tiffany showrooms until their contents were auctioned in 1938.