May 1 ...  Easter (Orthodox) ...

May 5 ... Cinco de Mayo (Hispanic) ... Commemorates a battle in 1862 won by the Mexicans against the French.  In the US, various fiestas are held featuring parades, food, musical events and dances.

May 5 ... Ascension Day (Roman Catholic, Protestant) ...

May 6 ... Yom Hashoah ...

May 12 ... Mother's Day ... a celebration commemorating mothers.  This holiday is celebrated in the United States, Denmark, Finland, Italy, Turkey, Australia, and Belgium.

May 15 ... Pentecost (Roman Catholic, Protestant) ...

May 15... Armed Forces Day

May 23 ... Declaration of the Bab ... celebrates the beginning of the Bahai faith

May 24 ... Viskha Puja (Buddhist) ...

May 30 ... Memorial Day (US Federal holiday observed) ...  US holiday first celebrated to honor the dead of the Civil War but has come to include lives lost in all the wars fought by the US.