I am guessing this is a tray once sold in tourist shops, and they would stamp their respective cities on the bottom; this one is stamped New Orleans, LA. The “blue willow” pattern featured on the tray was very popular in the early 20th century on china/Chinoiserie dishes, called “blue willow” because the dishes were blue and white and feature a willow. There are many variants on the engraving/painting. And given this is not china, and it’s not blue, it’s more of a “brass willow.” Very patinated, the motif is hard to see, but I’m a patina junkie, so if you want shiny brass, that’s your job. Based on the ring in the dish, someone last used it as a coaster. Measures 4.5” across, and is just over .5” high.