I am obviously not allergic. I didn't know what this was when I photographed it. Still not convinced, but that was the consensus of FB's Plant Identification group.
Huge poison oak cluster growing on live/blue oak stump /w live/blue oak still barely alive
Toxicodendron radicans has deciduous trifoliate leaves with three leaflets. Leaf color ranges from light green to dark green depending on maturity of the leaves. During the fall months color can change to various forms of yellow and red. The leaflets may become shiny with maturity. The leaflets usually measure between 3–12 cm.
Toxicodendron a genus of flowering plants in the sumac family, Anacardiaceae. It contains woody trees, shrubs and vines, including poison ivy, poison oak, and the lacquer tree. All members of the genus produce the skin-irritating oil urushiol, which can cause a severe allergic reaction. The generic name is derived from the Greek words τοξικός (toxikos), meaning "poison," and δένδρον (dendron), meaning "tree".