Andyrew wrote: When ever wild flowers grow in my lawn, I tend to mow around them until they're done flowering. Then I mow them down until the next year. One day, years ago, I was walking around my yard. To my surprise, I saw a wild "Black"-eyed Susan opening with a green center.
I saved it's seed and planted them the next year. A very few were also green-eyed. Now they are in abundance.
Then, about 6-8 years ago I brought home from work a short, large flowered, fully bronzed (or red) Rudbeckia. It wasn't very winter hardy, but produced abundant seeds. I kept it in the pot and set it in amongst a profusely flowering wild one (not green-eyed). The rest of the story is easy to figure. Now, wild ones regularly pop up with some reddening.
Interestingly, crossing the two types produce flowers that look "normal".