These used to be all over Santa Monica on my walk to and from school. I was told they were poisonous, but I've discovered that is ubiquitous adult-speak for "I don't know what those are exactly so don't go putting one of your mouth just in case." I can tell you they stain sidewalks and clothes like the dickens - which is good when you're trying out native dyes as a kid and are thrilled with the results yourself, but not always as well received by the parent doing the laundry...