What's your best potluck recipe?

I tried searching and to my surprise didn’t see another thread on this.

Tomorrow evening I’m attending a Groundhog’s Day potluck and am not yet decided on what to bring. So what’s your favorite potluck recipe?

I am personally only interested in vegetarian dishes, although perhaps some other omnivores would benefit from meat dishes if you’re eager to share.

Bonus points are being given for spring-themed dishes.