Nick's Extreme Pest Control was called to the house in Glen Ellen.
And here's where it gets nutty.
MORE: 'Birdseed Lady' speaks out on excessive piles of seeds dumped around SF neighborhood
Workers say the woodpecker was making holes to store its food, which kept falling into spaces in the walls.
When they cut into the wall, over 700 pounds of acorns were discovered.
The company posted on Facebook that there was eight bags' worth of acorns stuffed in the walls.
"Never came across anything like it," the post said.