I was just looking up this very subject this afternoon.
I have a lot of volunteer sunflowers this year thanks to the birds. I know from the one that volunteered last year that bees like them. So, I was inclined to let all of these new ones stay for the season.
But some of those seeds were dropped into some of my containers, and I don't want those plants to be affected. So, this afternoon, I pulled them out of the containers just to be safe.
@cosmosist That information is quite interesting!
While we are on the subject of sunflowers, I also recently read that they can be useful in cleaning up chemicals in soil. Since I've only been here a short time and don't know what chemicals may have been used on the lawn and in flower beds in the past, that information is intriguing.