|"Meal at which all people present share dishes they brought"? Potluck.
I like potlucks, their casual spirit, the egalitarian touch. Very American. Everybody pitches in, no one has to feel bad because one family or even one person had to do all the work. In Austria potlucks are not really common; there is not even a German word for the concept. It could be Kesselglueck - literal yet somewhat charming - but that term doesn't exist. On the web I found "Potluck: großes Abendessen, bei dem sich alle Anwesenden selbst mitgebrachte Speisen teilen" (translation from Reverso). This describes the idea accurately but it is a bit long.
For those of you who don't speak German, here's a re-translation, phrased as an invitation: "Please join us for a large evening meal at which all people present share dishes they brought themselves." How does that sound?