Short answers, pulled from the story.
The Floralia festival took place from the 27th of April to the 3rd of May during the Roman Republic era. This ancient event included theatrical performances and the release of hares and goats as part of the festivities. Crowds were pelted with vetches, beans, and lupins, creating a chaotic and vibrant atmosphere.
Saint Walpurga was officially canonized on the 1st of May 870. This date marks the commemoration of Walpurgis Night in Germanic countries. Folklorist Jack Santino notes that her day and its traditions are traceable to pre-Christian celebrations that took place at this time.
Charles II reinstated May Day celebrations in 1660 following the restoration of the monarchy. The holiday had been abolished and banned by Puritan parliaments during the Interregnum. This restoration was a symbolic return to the old ways and a celebration of the monarchy and traditional social order.
King Charles IX of France received a lily of the valley as a lucky charm on the 1st of May 1561. He decided to offer a lily of the valley each year to the ladies of the court. At the beginning of the 20th century, it became custom to give a sprig of lily of the valley on the 1st of May.
The first Lei Day was celebrated on the 1st of May 1927 in Honolulu. This holiday was invented by poet and local newspaper columnist Don Blanding to celebrate island culture and the culture of the Native Hawaiians. Leonard Red and Ruth Hawk composed the traditional holiday song May Day Is Lei Day in Hawai'i.
Pope Pius XII chose the 1st of May as the feast day for St Joseph the Worker in 1955. This date was selected as a counterpoint to the communist International Workers Day celebrations on May Day. The choice was a deliberate move to reclaim the day for religious and traditional purposes.