Different kinds of packing businesses
If you're interested in researching the packing business before 1920, this is an interesting document: a USDA report where different fruit packers describe their businesses in their own words. Several of the California ones are citrus businesses. I'd found it trying to track down information on Stewart Fruit. They turn out to be a marketing agency/commission packer that didn't actually take ownership of the fruit but instead added a flat 7% charge on sale prices in eastern markets to cover the packing, transportation, and marketing. There's also an entry for the California Fruit Grower's Exchange (Sunkist), Earl Fruit, and several other vegetable and fruit packers in California.
There was also one telling story in the Santa Clara County Fruit Exchange's entry. The Fruit Exchange was primarily a dried fruit packer; they disappeared by 1911 or so, and one citation blamed farmers only selling to the exchange in bad years but not selling in good years. Philo Hersey, president of the exchange, put it more bluntly: "This high average price was not satisfactory to our members, however, because they did not get the highest price paid anyone acting independently during the season."
Full citation: U.S. Department of Agriculture Report #98: Systems of Marketing Farm Products and Demand for Such Products at Trade Centers], 1913.