I've walked past this tree several times assuming it was a valley oak. Today I actually took a closer look and the leaves are kind of strange. And it has the mistletoe species which apparently prefers agrifolia and berberidifolia: http://www.inaturalist.org/observations/1832636
Perhaps this is a hybrid between lobata and berberidifolia (which some sources would call x macdonaldii, though that name really refers to an island endemic hybrid between Quercus pacifica and lobata), the leaf texture and rough edges do suggest that and both species are very common here.
Poison oak can be found in the form of shrub or vine.It causes skin rash in many people. It can reach 4-5 feet in height as a shrub.
Weed in lawn