The Rock Hollow Barn is easy to find, and located away from the busiest streets of the Lavender Fest:
Go West on US101 and turn left (South) onto River Road. Then turn left (East) on East Silberhorn Road, proceed to 505. It will be on your left. Click on the image below to enlarge:

Art Jam 2014 - Google Chrome 5182014 44411 PM