Clementines are good, but it seems like they are not as good as they used to be? Blood oranges are good too. I am weird about citrus - I have to peel off all the white cruft, and peel each individual section. Except for clementines, which have a thinner membrane. So a lot of work/mess but still good. Luckily I get vit c from other sources. I've seen Buddha's hands but have not looked into what to do with them - they don't look very fruity.
For kumquats, I again suggest the Asian groceries. Good produce in general.
But yeah California roadside stands - strawberries in season, avocados that have flavor, sigh.