Regarding organizations … I would suggest contacting West Seattle Helpline. They probably don’t accept such things themselves but would certainly be plugged into nonprofits in need
http://wshelpline.org
Or … looks like Salvation Army picks up. I just ran through the first couple steps to schedule a futon pickup in West Seattle and while the lead time is a week-plus, it looks like they do it. In our area, for example, they have a shelter for domestic violence victims.
https://satruck.org/Donate/choose
Thanks for wanting to give.
TR