We use to have annual block parties at the first house we lived.
In our flier we mentioned for attendees to bring their own plate, eating utensils and a dish to share. We never had anyone not understand this. You could say a food dish to share. ???
We always had a donation jar. Whatever was put in at the end was saved for the following year to buy (non-alcoholic) drinks and fireworks.
So along with the other items, we mentioned soda, ice tea and Kool-Aid would be available. If they wanted any thing other than that it was BYO.
We kept ours very family oriented.
We had White Elephant Bingo, asked anyone who had an ice cream maker to bring one and had a homemade ice cream contest, fireworks, etc. There were committees.