The personification of May does not originate with Hawthorne. The English word "May" comes to us through Middle English and Old French from the Latin Maia. In mythology Maia was the daughter of Atlas and the mother of Hermes (Mercury) by Zeus (Hamilton 39). She is identified with Faunus, a Roman goddess whose "festival took place on the first night of May, and was celebrated with wine, music, merry games, and mysterious ceremonies, at which only women and girls were permitted to be present" (Murray 140).
Hawthorne identifies the revelers of Merry Mount with a pagan deity to mark the contrast between them and the dour Puritans who came to build a new Jerusalem.
Hamilton, Edith. Mythology. New York: New American Library, 1953.
Murray, Alexander S. Manual of Mythology. Detroit: Gale Research Company, 1970.