28th April - 3rd May is the Roman festival of Floralia celebrating fertility of flowers and crops. The first records go back to Rome in approximately 238 BC.
Over the years this developed into a celebration of sexuality, and probably influenced the subsequent celebrations for Beltane and May Day. Bright coloured clothes (if any) are worn, races and shows were performed.
Further Information
Follow the link for more information http://projectbritain.com/calendar/April/floralia.html