Catherine Creek Trails, Klickitat County, Columbia Gorge. April 27, 2013. I am having a little trouble with this one. Seems very common though.
Trifolium wildenovii (listed as Trifolium tridentatum in Wildflowers of the Columbia Gorge). I can think of nothing that somewhat resembles onion in both flowers and leaves in the PNW that will be harmful to the touch -- look for linear-ish or strap-like leaves (this would have eliminated Allium quickly here, as you would have recognized the leaves as being 4-leaf clover like) and the ball-head, then crush the tip of a leaf (so as not to do too much damage) -- if it smells like onion, it's an onion.
