Western poison ivy

Toxicodendron rydbergii. The western form of poison ivy does not grow as a vine - it is always a small shrub (though reportedly a small tree in some scattered locales).

"Leaves of 3 - let it be" encompasses several innocuous plants, but will keep one out of poison ivy. Typical growth habit is for the three leaflets to droop down from the end of the branch, as seen here.