The 15th of May is the date for the Roman Festival of in honor of Mercury or Mercurius, whom they also identified as the Greek Hermes. The Greeks themselves would relate their Hermes to the Egyptian Thoth and Anubis as well, so the Mediterranean was basically filled with people placing their gods all over the place.  A pretty swinging place.
I make a point of honoring Hermes in a multitude of his forms, and today being the festival of one of them, I just thought I would share. To this, I also give you my version of the Orphic hymn to Hermes.

Hermes, draw near, and heed my prayer,
messenger of Zeus, and divine son of Maia;
Master of Competitions, Lord of mankind,
all-powerful heart, joyful, guide and messenger,
possessing many skills, Slayer of Argus:
bearing winged sandals, aide of humanity, and teacher of language:
You rejoice in the gymnasium and in clever deceit:
ever changing, Able to understand all things, conductor of trade,
Whose skills help to lessen our problems,
Bearing the caduceus, that wand which can bring perfect peace,
Joyous, bestower of good fortune, skilled in persuasion
You aid us in our labors, and bring to us our necessities,
Having a sharp and deft tongue,  worthy of veneration,
Bestow upon us good fortune and the fulfillment of necessities
Through favorable speech and enduring memory