An interesting sunflower volunteered in my garden last year. It had a bunch of mutant secondary flowers all over it. They looked like conjoined twins, or like the blooms had been pinched so that they were squat. The main flower was about six inches and the plant was about six and a half feet tall, but it was all on it's own, so it might not do so well with a bunch of competition.

I managed to lose the pictures I took of it, but it was quirky and interesting.

If anyone is interested I'd love to share the seeds.