What kind of tree do I have?

If you could describe the leaf an identification would be more possible. As a wild guess, how about an Osage Orange. They definitely grow in your area. To see a picture go to

http://www.gpnc.org/osage.htm

Not to be rude, however, any plant (and I mean any plant!) that exist where you do not want, need, nor recognize is simply a weed!! If you had an acre of lawn and a marigold happened to pop-up you get rid of it. If you had a marigold garden and grass poped-up you get rid of the grass. Do yourself a favor and eliminate the plant immediately. You do not want it, do not know what it is, and have no way of telling it's effect on you, family, or garden. Again, a weed is any plant you do not want! Good Luck.

Short thorns, probably a hedgeapple or osage orange.

My guess would be Hawthorne it grows in the warmer parts of Oregon which is similar to the weather there

If the leaves are silvery, it may be a Russian Olive.

I think it is a type of locust... we have the same in our yard and they are like weeds!!!

get rid of it. Its a weed.