This is another fine mushroom that grows in our forests. It could be a Cantrell, but from this photo it's hard to tell. I try not to step on any or disturb them so that they might propagate and flourish, so I don't know what the underside looks like. The shamrocks are wood sorrel with the latin name - oxalis : http://en.wikipedia.org/wiki/Common_wood_sorrel . These have a burgundy red on their underside in late summer and they fold up at night to protect themselves. Up here in Humboldt County we have what we call " 'Shroom Season". Lots of people head out to the forest to gather scrumptious morsels for their dinner plates. It is but one of many seasons - like deer hunting season and duck hunting season ..... It's what we locals do for fun - gather in the harvest from the forest.