There are Farmer’s Markets everywhere in California. Just about every city, has several a week during the summer and fall, and many small towns also feature a once a week farmers market.
Here is a link to a Farmers Market resource for California.
Here is a list of Farmers Markets from Red Bluff to Redding, California.
The first list has just about every city in California, except Weaverville, California, and maybe some other small towns.
The Weaverville, California, Farmers Market is on Wednesday Evenings in the Meadow on Highway 299, next to the Highland Art Center. The market starts at 4:00 pm and goes until 7:00 pm.
Also when traveling in California, not on Interstates, but on the smaller local highways, you will find lots of fruit and vegetable stands. Highway 99 between Red bluff and Chico for example you will pass many stands. And also on Highway 20 from Marysville to Grass Valley, you will see one or two. And also on the highway 99 from Chico to Yuba City and Sacramento, Highway 99 you will find lots of fresh fruit stands, with nuts, dried fruits, fresh fruits and vegetables. Along with Jams, and whatever else can be made from the local fruits and vegetables. Careful driving on these highways! They are in the country and only two lanes.