The second Sunday in May is Mother's Day in most countries.
International Day Against Homophobia, Transphobia and Biphobia
The date of 17 May was specifically chosen to commemorate the World Health Organization's decision in 1990 to declassify homosexuality as a mental disorder.
Declaration of Bab (Bahá’í); Wesak (Buddhism) (NOTE: Celebration date varies regionally)
Extremely significant holiday during which observers typically suspend work and school. Declaration of the Báb; Wesak
108th running of the Indianapolis 500.