Just off highway 6 (between Portland and Tillamook) is a series of lovely campgrounds in the Tillamook State Forest. Gales Creek is the first one you'll find on your way coming from Portland, and it's one of my favorites. The sites are surrounded by trees, and, if you're lucky, you can grab one next to the cute river than runs through the camp. Enough fun things to do like hikes or play with the water pump. The bathrooms are nothing fancy, and there's no showers, but the price is also right ($15). The main issue is that all sites are first-come/first-served, and there aren't too many sites, so hard to get something on a nice weekend or a holiday. But if you can snag a spot, you're in for a nice time.