I saw this recently at a restaurant, using herbs instead of flowers as a centerpiece. I really liked the idea I thought it looked really sweet in a small vase. Something to do with left over herbs from cooking.
Although, this made me also think that this could be a great hostess gift to give someone; a bouquet of fresh herbs. I know I would be excited to receive a brunch of different fresh herbs tied with a bow. And if the person is not the biggest cook what about a bouquet of Fresh mint a very useful ingredient in a lot of summer beverages.