Mass. Gen. Laws ch. 134, § 1

Any person who finds lost money or goods of the value of three dollars or more, the owner of which is unknown, shall within two days report the finding thereof to the officer in charge at a police station in the town where said property was found, or, if there is no police station, post notice thereof in two public places therein, or, instead of such report or posting, cause notice thereof to be advertised in a newspaper published therein.