The flower attached to this post (peony) used to grow next to our house growing up. I saw some earlier today down the street from where I now live that reminded me of them. They're interesting (particularly when you're a little kid and anything related to bugs is very interesting) because ants will crawl all over the flower tips for days before they finally bloom. I assumed they're getting sugars or something similar and that it's a net positive for both the ants and plant that hosts the flower. A quick search online confirmed as much. The ants don't actually help open the buds (as I thought when young), but will defend the plant against other intruders. So there's that. A little sugar for protection.