Ol' Man,
Mussels abound here. With the correct fishing license, one can collect them. However, collection is quarantined from May to October over concerns related to red tide microbes. There are also more than one species of limpet (Opihi), but not the large black foot or delicious yellow foot you have in HI. I must look to see if these specific Opihi can be found on the ocean side of the Channel Islands.