Appendix D to The Return of the King lists the holidays from the article you linked above, namely three Lithedays (roughly Midsummer) and three Yule days (Midwinter). It goes on to mention that during the reign of Elessar the calendar was reordered, to commemorate the fall of Sauron on March 25th, and September 22nd, Frodo's birthday, "was made a festival, and the leap-year was provided for by doubling this feast, called Comare, or Ring-day." (Return of the King pg 447)
However,
There is no record of the Shire-folk commemorating either march 25 of September 22; but in the Westfarthing, especially in the country round Hobbiton Hill, there grew up a custom of making holiday and dancing in the Party Field, when weather permitted, on April 6. Some said that it was old Sam Gardner's birthday, some that it was the day on which the Golden Tree first flowered in 1420, and some that it was the Elves' New Year. In the Buckland the Horn of the Mark was blown at sundown every November 2 and bonfires and feasting followed." (Return of the King, pg 447-448)
It is worth noting that April 6 is listed in Appendix B of the same book as being when "The Ringbearers are honored in the the Field of Cormallen" and the next year as when "The mallorn flowers in the Party Field." November 2 is when Gandalf and the Hobbits "come to Bywater and rouse the Shire-folk." (Return of the King, pg 430-431)