Ya, she wasn't really a collector, she would just buy stuff she liked and wanted in her house. She never kept records of where she got stuff or what it cost, she just kept the things she liked and gave away the rest. They enjoyed China, and often told stories of being in warehouses of "rocks that look like mountains and bonsai." That being said, it could have come from an estate sale or antique shop in the Bay Area too, she picked up stuff all over the place, some very valuable, others imitation trash.
I have seen similar dishes/trays/pots/whatever on ebay in the $100-200 range, but the painting is not nearly as good, nor do they show the same age and wear. I have no intention of selling it, but often people selling things have better records of how old the thing is and where it came from.