I see this flower growing wild by the sides of bike trails and walking paths in the San Francisco area and throughout central and northern California. It is very common but I've looked online and have never been able to find it identified. Attached is an image. I've seen it with white, pink, lavender and yellow blossoms. Thanks!
Thank you for the answer to my question and the link to the image. That's exactly the plant I was talking about -- Raphanus. I appreciate your solving this mystery for me. It's been bugging me for years now!
