Some WIld Radish (Raphanus sativus), photographed along the Heart's Desire Trail at Coyote Valley Open Space Preserve in southern Santa Clara County, CA. Note that there are three photographs in the set of pictures documenting this specimen:
Shot 1: A close-up of the flowers, both open and closed.
Shot 2: A moderately tight shot of the upper stems and cauline leaves, one of the plant's inflorescences, and some young seed pods.
Shot 3: A fairly tight view of the plant's lower stem and basal leaves.
This particular specimen has these odd bristles on its outer calyces and along its main stems, which I have never noticed on this species before.