There is only one place in the U.S. where four states meet.
But what about counties?
In California, there are two such spots. The two sets of four counties in question are:
1. San Luis Obispo, Monterey, Kern and Kings
2. Santa Clara, Alameda, San Joaquin and Stanislaus.
There are a couple more that might appear to qualify, but if you look at them closely on a map, they don't quite meet up (merely instead forming two nearby spots where 3 counties meet). For it to truly be a four-corners meeting, two map lines must cross each other cleanly (not necessarily at 90 degree angles, as they do at Arizona, Utah, New Mexico and Colorado). While it is possible to make a map where more than 4 areas come together to meet at a point, there are no "5 (or more) corner" spots in California.
So, there you go.