Any idea what this plant is?
Hello, that is oak mistletoe, Phoradendron villosum. Did you find it under an oak tree? Once the leaves fall off the oak this Autumn, you will notice lots of these shrubs up in the oak canopies in the Willamette Valley and south through California..
Here is an information sheet about mistletoe of hardwoods: http://dnrc.mt.gov/divisions/forestry/docs/assistance/pests/fidls/147.pdf
this includes some info about oak mistletoe.
The plant is a parasite on oak, but unless there is a large number of plants , it likely does not hurt the tree too much. Also, the berries mature in December and provide winter food for western bluebirds!
Therefore, the plant can be considered a pest or alternatively, good for wildlife.
I hope this is helpful.