Finding any lichen ID matches online is a challenge, even with a public-friendly common name such as dog lichen. Apparently, there are some dog lichens that are considered pests on lawns. Who knew? I didn't find an exact match for this lettuce-leafy specimen with chalky white back and blistery reddish-orange nodules scattered across the top surface (yes, my own descriptive words). I also have pictures (sorry, not posted) of this same-looking dog lichen from Stevens Creek on February 10, 2014, which makes me think it must be fairly common in the Santa Cruz Mountains. I'm guessing many ID'd photos online may be incorrect to sp. However, I did find a couple decent dog lichen photo series on Stephen Sharnoff's Lichens Index 9 and Andrew Khitsun's Lichens of Wisconsin (for both sites, do a find for "peltigera" to quickly get to spot on page). I've added their home pages to my online ID resources under fungi, lichens, and slime molds.