I had my own mini-adventure by taking a solo trip out to the Cottage Grove Bike Park. They seemed set-up for pump track only right now, but you can see the bike park taking shape and I believe they just earned a grant to have IMBA trail builders help them improve it all.
The pump track consists of two distinct portions, far as I can tell, one for beginners with smaller smooth bumps and another above it on the hill that had bigger berms and bumps. Both are quite smooth, fun, and a great way to get a feel for a your bike and how to keep your momentum going. Riding without pedaling on them, which is the idea, can be a challenge, but a fun one.