Apparantly 'Blue Moon' has 'traditionally' been attributed to the Maine Farmer's Almanac.
Blue Moon - Wikipedia

The term has traditionally, in the Maine Farmer's Almanac, referred to an "extra" full moon, where a year which usually has 12 full moons has 13 instead. The "blue moon" reference is applied to the third full moon in a season with four full moons,[2] thus correcting the timing of the last month of a season that would have otherwise been expected too early. This happens every two to three years (seven times in the Metonic cycle of 19 years).[3] The author of a March 1946 article in Sky & Telescope attempted to decipher the traditional practice of the editors of the Maine Farmers' Almanac by examining old issues of the almanac. Without enough almanacs to see the correct pattern, he conjectured the wrong rule for 'blue moons', which led to the modern colloquial misunderstanding that a blue moon is a second full moon in a single solar calendar month, with no link to the order it occurs in a season.