What part of Oregon. In the field? At a shop? Knowing location and circumstances is helpful.
There is an area, in central Oregon, generally known as Hampton Butte, where green petrified wood, or varying quality, can be found. There are other locales where green jaspers are not uncommon. There are a few areas that are little known where copper ore specimens can also be found. Then there is green serpentine, which is widely scattered across southwest Oregon and parts of the Coast Range.
When you let us know where and the circumstances of finding your rock, those of us familiar with the region can better help you.
Time for lots of coffee.