Notice the long, tapering tips on the fronds
A fallen log is decked with soft green ferns. This is licorice fern (Polypodium glycyrrhiza)–a confusingly close relative of the much more common California polypody. Licorice fern can be identified by the tapering, pointy tips on its fronds and–at least according to one guide, Plants of the San Francisco Bay Region–the veins on the fronds are translucent (while California polypody veins are opaque and the leaf tips are rounded). As far as I can tell, both of these two polypody species have rhizomes that taste like a tart licorice–but I’ve only done my taste-tests haphazardly, and so might be wrong.
Native Americans chewed the tasty rhizomes for flavor, and also used it to treat colds and coughs, and venereal disease. 
Flowers Of Marin 