Found in Gingko Petrified Forest Hiking trail, next to parking lot (under neath the 'parking' sign actually). Only specimen seen, though I didn't hike the whole trails. Large, flat, pad forming, but it looks like the flower has a green stamen?
Looks to me what is usually called Opuntia x columbiana. Here's a traveling account of cacti in eastern Washington, including mention of an expectation to find the above entity at Ginkgo Petrified Forest.
