Tucker Park Near Hood River
We stayed here at Tucker park. It was nothing fancy, and its not free, but its cheap enough, and a nice quiet campground. its @ ten minutes out of hood river on the west fork of the Hood River. we looked at other ones that were right on the freeway in the gorge, and were loud, traffic echoing.
there is some free camping at the bottom of the hill, down on the columbia river, literally on the water. on a spit of land right by where they kiteboard.
There has to be lots of camping on the washington side.
Tucker Park is easy though, and there is some amazing orchards, right there with bomb preserves and stuff.