Shelf fungus

Oh, these make spectacular bramble thickets! This is just the tip of a growing cane; if it's left alone, this whole log is likely to be engulfed in a thicket in a couple of years. IIRC there are two species of blackberry in the Seattle area, a native one, and an exotic (Himalayan blackberry was the local name), which is more invasive and has canes with thorns like scimitars. But it also has better fruit-- What I remember is that the canes last for 2 years--the first year they grow, the second they flower and die. But the plant itself is perennial, because it's always putting out new canes.

The Himalayan blackberry in particular is considered a noxious weed in the PNW. We pulled lots of them out of our yard when we lived outside Seattle. If you want to use them for berries, you really need to keep them trimmed and trained so that you don't end up with an impenetrable thicket.