FTI, there are no admission or other fees for:

Public clamming, with a fishing license, in Drakes Estero, a large shallow estuary on the northwest side of the Pt. Reyes peninsula.

Mushrooming for personal use everywhere in the Pt. Reyes National Seashore, though for all practical purposes is mostly done in the mixed oak-pine forested areas on the east side of the long ridge, away from the ocean.

Edit: if I had a small boat and crab traps or hoops, I know where to go in Tomales Bay to get red rock crab. Tomales Bay forms the eastern boundary of Pt. Reyes, and is separated from Bodega Bay to the north by only a shallow sandbar. Bodega Bay opens onto the Pacific Ocean. Maybe next time out of my kayak.