Randolph Collier Rest Area I-5 MP 786 Klamath River Rd. Probably one of the nicest rest areas anywhere. Its about half way between Yreka CA and Ashland Ore next to the river. If you go to the back it is reasonably quiet and has plenty of room. Have spent many nights there. This is not a campground, arrive late, leave early.
As far as Rolling Hills Casino is concerned the $28 for a campsite is worth it as opposed to staying with running reefers and smelly cattle trucks. They do have what is probably one of the best buffets anywhere and if you are over 50 it is half price on Tuesdays and Thursdays.