What to bring for Pot luck party?

This is requested by my sister May. She is attending her friend's house pot luck party and ask me if there is anything I can help her to do. The criteria has to be simple and nutricious.

I thought sushi & onigiri is a good ideal. These rice ball is low in fat and is a very nutritious food; decorated with cherry tomatoes, as they are rich in vitamin C and other antioxidants.

Hope her friends will like it.