Medium Round Silver Platter by the International Silver Company

Well, unless its stamped "Sterling" it would appear to be silverplated and a pretty standard type of platter made for much of the 20th Century by International silver. The design's loosely based on English 18th Century Georgian examples, but most likely dates from the second quarter of the 20th century. Values for silverplate is very modest at present, serving trays like this often sell for under $20.00 at auction