DW makes a list before getting to one of the Ca. inspection stations. Last year we got asked about firewood for the first time but they didn't want to inspect it and had barely stopped before we got waved through.
Crossing the Can/US border is a different matter. Got pulled aside a few weeks ago for a random inspection. They went through every single piece of firewood (all processed/sawn lumber) and found a tiny bit of bark on 2 pieces of kindling and got a stern warning. Funny thing was the wood was all from Wa. state. I also had 6 strawberries that I intended to eat before I got to the border but forgot about them. When asked about fruit, I told them about them and escaped a $500 fine. If you have Nexus and they find fruit you didn't declare, they can even take your Nexus away from you permanently. Seems like just about all of our fruit comes from the US but you can't take it back there. :(
Going through a Ca. inspection station is one of those interesting and uniquely Californian things and I don't mind them at all.