I found this fungi growing at the edge of a dead log in a park near my house. There was no stems or gills but the cap shape was a conchate (sea-shell) shape with an undulating cap margin. I would say that the cap surface was uneven (bumpy)

To me, this looks like some type of polypore/shelf fungus. From looking at different resources, I found that this mushroom closely resembles Abortiporus biennis. This is because they both have similar cap colours (with a white border) and they both also contain greyish-white type of pores on the underside. A good photo of Abortiporus biennis can be found here: https://www.alpental.com/psms/PNWMushrooms/PictorialKey/Polypores/Abortiporus_9084.htm

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