From a small collection of pressed glass mugs I purchased recently, this toy or child's mug is of slightly opalescent/translucent milk glass. It has a peacock on one side, and a heron or stork on the other. Haven't been able to identify, but I suspect this is an Atterbury glass company product of the 1880's.
Size: Approximately 2.5" high.
Condition: Some roughness around top, chip on foot. No other chips, cracks or repairs.
Note that I try to be conservative about condition descriptions, carefully noting any flaws. Of course, with antique items, there will be some signs of usage, and/or manufacturing defects. But overall, my customers have always been pleasantly surprised upon receiving their items, and of course, returns are no problem if I happen to miss anything.