For most of my 64 years, I have believed that sunflowers turned their heads during the day to follow the light. I grew up in an area where the sunflower fields went on for miles, and I loved how they turned to face the sun through the day.
So I was puzzled to find that the flowers in these fields don't turn. They are facing the same direction at 7:30 in the morning and 2:00 in the afternoon and 6:00 in the evening.
I fretted about this, was pleased to see in some of the pictures that a few small flowers knew enough to turn their heads, and finally I broke down and googled.
I learned that young sunflower plants turn their heads to follow the sun, but after they are mature, they face east all the time. No turning. And sure enough, the sunflowers in these fields are facing east with the exception of some of the small ones.
Another myth from my childhood (and adulthood) gone by the wayside...