Oregon's herp laws are very progressive and nonregulatory...should not be an issue if you can collect them. I would just look and collect some small plants from around where you find the salamanders and give them a try.
I have kept these in the past, I kept about 60-70% humidity, and no water hole, if you keep enough super damp dark hiding places, they do fine. MAKE SURE YOU HAVE A SECURE LID red backs can climb, and are escape artists. They actually do not even lay their eggs in or near water. Very interesting and fun pets. Good luck! (Greetings from Wisconsin)