Gopher snake? It was dead, laying in the full sun, could have turned this dark color after death?
Valencia Peak Trail, Montana de Oro State Park, Los Osos, CA. Good-sized snake, was rattling loudly for several minutes.
Carrizo Plain
Very docile..had a hard time getting him to move off the road and I'm not that confident yet to pick up snakes though I did "pet" it.
Close to the area where P. catenifer catenifer occurs...but this location wasn't too far from the coast..within the range where P. catenifer annectens is found (looks like an annectens to me).