There was a day when just about every New England town had a small dairy, or several, at minimum. Before the days of pasteurization, fresh milk was delivered to homes on a daily or weekly basis. Many municipalities required dairies to register their fleet vehicles, and some provided permits displaying information such as registration number, year of validation, and town or city of issuance.
This 1929 porcelain milk plate is likely from Fall River, Mass, based on gathered information and anecdotal remembrances. This is the only one of this type in my collection, examples are known back to about 1912.