Hi Holly,
I used to live in Reseda so whenever I felt the need for beach hunting Malibu was always a good spot to go. The beach on the north side of the pier has produced some silver rosies for me at low tide, but sometimes they come out pitted. I've found a 14k watch and some silver jewelry also at same spot. Never been up Malibu creek, though. Good luck and let us know how you do!
Ray