Bilbo's Farewell Party
Bilbo's Farewell Party was a grand celebration held by Bilbo Baggins on in 111st birthday in the Party Field. It was coincidentally also the 33rd birthday of his nephew Frodo Baggins. As recounted in A Long Expected Party, it was a huge and expensive celebration attended by most hobbits in the area, but a portion of the party was "invitation only" with 144 guests. The party included copious amounts of food and drink, and Gandalf the Grey provided fireworks for entertainment.
The occasion was notable in Hobbiton for Bilbo's abrupt disappearance (he used the Ring to disappear at the end of his birthday speech), but the most historically important event was Bilbo leaving the Ring in Frodo's keeping when he departed.