Mormon New Year (April 6th)
What celebrated: Organization of the Church in Fayette. LDS tradition hold this is also the birthday of Jesus, but some dispute this. Because of its special place in LDS tradition, various events were aligned to fall on it, such as the St. George and Salt Lake Temple Dedications and the annual general conference of the Church for many years always fell on this date (but back then, there were even more sessions than the current five).
How to celebrate: Cupcakes. Cupcakes for Jesus.
Martyrdom or Joseph Day (June 27th)
What celebrated: The deaths of the Prophet Joseph and his brother Hyrum in Carthage Jail. Being held after ordering the destruction of the anti-Mormon Nauvoo Expositor's press, Joseph and others were attacked by a mob bent on his death. Final words "O Lord, my God..." may or may not have been the start of Masonic identification of assistance.
How to celebrate: Please direct questions to Petra. Despite strident pleas and the fact that we were actually together for one Joseph Day, she has yet to take part in the traditional form of recognition.
Pioneer Day (July 24th)
What celebrated: Though the scouts for the pioneers entered the valley on July 21st (pls note: the fact that alea was also born on that date must be no mere coincidence), this is the day that Brigham propped himself up in his wagon and said, "This is the right place. Drive on." Mormons had finally found a land that truly no one else wanted (Tony Kushner later writes one Mormon character as saying "It's a promised land, but what a disappointing promise"). In the tense days leading up to the Manifesto, proposals of shifting settlement south to Mexico, north to Canada, west to California or Oregon, or far, far north to Alaska were considered. For everyone who complains about Utah, keep that last one in mind. We could be centered in Alaska.
How to celebrate: Parades, bbqs and, of course, fireworks. It helps if you can lord over others the fact of your personal pioneer heritage.
Haun's Mill Massacre Memorial Day (Oct 30th)
What celebrated: The attack on Mormon settlement at Haun's Mill, Missouri (settled contrary to the wishes of Church leaders). Not much in the way of a massacre, really, as the death toll was around 20 with a dozen or so wounded.
How to celebrate: Inform those around of the day. Breathe cursings out on Missouri.
Utah day (Jan. 4th)
What celebrated: Admission of Utah into the Union as the 45th State, a mere 49 years after first Mormons arrive (and after a measly 8 attempts at statehood).
How to celebrate: party/meal of Utahn foods. Funeral potatoes and some sort of jello required.
Three Degrees (Feb. 16th)
What celebrated: Joseph & Sidney Rigdon's 1832 vision (recorded as section 76 of the D&C) of the Three Degrees of Glory. Thanks to this vision, and subsequent enlargements by prophets, Mormonism does not have a proper hell and the overwhelming majority of mankind receive some form of salvation.
How to celebrate: Something baked, possibly ironic. A good example is cookies in the shape of the symbols of the three degrees (sun, moon, star).
Holidays under advisement
Ministering of Angels (May 15th)
What would be celebrated: The appearance of John the Baptist to Joseph & Oliver. He restores the Aaronic Priesthood and Joseph & Oliver later baptize each other. Joseph has the odd experience of baptizing someone before he himself is baptized.
Revelation (June 1st)
What would be celebrated: Announcement of the revelation to Spencer W. Kimball that members of African ancestry can hold the priesthood. Reverses nearly a century and a half of Church practice and its attendant horrors of justification for the ban by lay members. Note: it is my personal opinion that one reason Harold B. Lee's presidency was so short was to hasten the time of this change.
Miracle of the Gulls (June 9th)
What would be celebrated: Miraculous (though use of term somewhat contested) appearance of seagulls to gorge on crickets attacking Utah pioneer's first crop. Supposedly, the birds would eat their fill, fly off to regurgitate and repeat (one is tempted to say ad nauseum but will refrain).
Call of Joseph (Sept. 21)
What would be celebrated: Visit of Angel Moroni to Joseph, first recorded vision since famous First Vision. Joseph, up to this point, had been told all churches were wrong, but seems a bit uncertain what to do with that information. After this point, he actively begins preparation/training to translate the Book of Mormon and fulfill his prophetic destiny.
Endless Genealogies (Nov. 13th)
What would be celebrated: Date of the establishment of the Genealogical Society of Utah, but could be more broadly focused on the efforts of the Church to seek out and save as many dead as possible. Mention of the Granite Vaults would be encouraged, as would temple worship for the deceased.
Mormon New Year (April 6th)