Thanks for looking.... I have put this piece in the junk pile twice, But I keep pulling it out. Found in SW Oregon, Western Cascades, Miocene, Little Buttes Volcanics.
Measures about 30mm by 25mm, Here is a link to the site it was found, in fossil hunting trips.
The piece was already split open on the ground and I did not look for other pieces, Because it looked like a stain?