McKenzie Pass is what I remember, after looking at a map. Highway 20 between Sisters and Cascadia.
On the drive from Bend to the coast there's a pretty spectacular lava field. Is that it?
That's definitely not the Newberry Crater flow; you have to take a road east off highway 97 to get there. Well worth the trip. I see a couple different lava fields on the map west of Bend, so you'll have to be more specific about which highway you're referring to.
No, it is more south and a little east of the highway. Huge flow of obsidian, not what we think of lava, this is black glass. On top there are obsidian boulders almost the size of a Smart car.
A ways from there, there was a lava flow with casts of trees, that left round voids down into the lava.