Potluck

A potluck is a gathering where each guest contributes a dish of food, often homemade, to be shared. Synonyms include: potluck dinner, spread, Jacob's join,Jacob's supper, faith supper, covered dish supper, dish party, bring and share, shared lunch, pitch-in, bring-a-plate, dish-to-pass, fuddle, and carry-in.

The word pot-luck appears in the 16th century English work of Thomas Nashe, and used to mean "food provided for an unexpected or uninvited guest, the luck of the pot." The sense "communal meal, where guests bring their own food," appears to have originated in the late 19th century or early 20th century, particularly in Western North America, either by influence from potlatch or possibly by extension of traditional sense of "luck of the pot".

Potluck dinners are events where the attendees bring a dish to a meal. Potluck dinners are often organized by religious or community groups, since they simplify the meal planning and distribute the costs among the participants. Smaller, more informal get-togethers with distributed food preparation may also be called potlucks. The only traditional rule is that each dish be large enough to be shared among a good portion (but not necessarily all) of the anticipated guests. In some cases each participant agrees ahead of time to bring a single course, and the result is a multi-course meal. Guests may bring in any form of food, ranging from the main course to desserts. In the United States, potlucks are associated with crockpot dishes, casseroles (often called hot dishes in the upper Midwest), dessert bars, and jello salads. Traditionally, potlucks were a simple combination of dishes brought together by event attendees without a general theme. However, recent times have seen the growth of themed dinners for parties or special occasions.

...
Wikipedia