Old-Fashioned Potato Beetle larvae (known here as "bugs in outfits") also feed on this plant.
Wikipedia lists Jimsonweed or Datura wrightii as poisonous. It is also a known hallucinogenic.
Disclaimer: The Corralitas Red Car Property Blog prefers to quote reliable sources, such as Calflora and California Poison Control, on the issue of toxicity. We often get email suggesting some plants are edible. We DO NOT recommend you eat any plant you find in the Red Car Property neighborhood without first doing your own research.