Bassist Kevin McCarthy's group hosts the Sunday Jazz jam at Darrell's Tavern in Shoreline. They ask a $5 donation to musicians. Darrell's is a comfortable tavern in the American tradition; friendly folks, plenty of room, pinball and pool for those who want to enjoy those things, good beer.
I have cross-posted this listing from the Seattle Jazz Scene meetup both as a way of encouraging our members to join their meetup and also to make folks aware of this high-end jam session. By all means, call Darrell's Tavern to make sure the event is on; I am posting but not necessarily able to go to this every week.
By the way, I just met Kevin at a private function, and he and his cats were happy to chat and play with us amateurs, and awesome to listen to.