Find out what the laws are in your state for trespassing. In CA, you are only trespassing if you are asked to leave and you didn't leave. It might be the same for you in OR. Know your laws. And don't give anyone your ID or other info. You are only required to do so when you are being detained by law enforcement.
I think it's kind of funny though that he wants you to leave, but then he wants you to stay at the same time.
Oh yeah, I'd contact the property owner and request your property back from him.