Identification: ID, pls: Sheet-like fungus on Big Leaf Maple

Hello.
Can you tell me the name of a common Pacific Northwest fungus that typically grows on Big Leaf Maples in association with moss and licorice fern? It grows in clusters of deeply lobed "sheets" up to perhaps 8" long. Texture is distinctive -- a web of shallow pockets. Topside is creamy white, aging/drying to brown;underside is rich yellow-green. I make paintings, often with botanical themes, and these are an amazing subject! Thank you, Kelly

 

Does it look something like Lobaria pulmonaria?