Here is another photograph from a favourite area of mine in California, taken on April 5, 2010 (the same day as this photograph). Instead of identifying the plants when photographing these areas, I tend to just spend my limited time behind the camera. Fortunately, others who have the opportunity to spend more time with the plants have added some documentation, so I think it is relatively reasonable to use resources like Nature Alley to assign some names.
The small yellow flower that dominates the image is certainly a Lasthenia, or goldfields, but I would feel very uncertain assigning it to species. The purple inflorescences belong to a Castilleja, probably Castilleja densiflora. Resources for the area suggest that the remaining white and yellow coloured blossom is almost certainly the broadly-distributed Layia platyglossa.