This is citrus season in Orange County. There are very few commercial citrus groves here now - their place has been taken by what SCalifornia grows best, houses and shopping malls and freeways. But there are citrus trees of many kinds in back (and front) yards.
This is a very young kumquat tree, only about six feet tall, but it has a bumper crop of fruit. It grows in the front yard of a neighbor. I don't know if she uses the fruit, personally I don't find it appealing raw, but I love kumquat marmalade. I haven't made it for years though there are lots of kumquat trees around and the owners would share fruit. No incentive, I guess.
The fruit will fit comfortably in my cupped hand. Although I didn't notice until I downloaded the photos to my computer there is a mayfly on the leaf. Perhaps that will give you a good comparison for size.
Here is a blog with a post about kumquats that I found interesting:
http://tinyurl.com/c3q3rv
