The Floralia, which was celebrated in Rome from April 27th to May 3rd, is a festival which honors the goddess of flowers, Flora, another manifestation of the earth-goddess which includes Fauna, Maia and Ops.
The temple of this goddess was founded on this day on the Aventine. Offerings of milk and honey were made on this day and the surrounding five days, which comprise the Florifertum.
The city would have been decorated in flowers, and the people would wear floral wreaths or flowers in their hair. Games would be celebrated on this day. The celebration of this day survives in many cultures where it is known as May Day.