Tree Identification - California Bay Area
For California trees, my go-to is A Californian's Guide to the Trees Among Us by Matt Ritter (Heyday, 2011).  California trees can be challenging due to the extremely varied habitat and many introductions over the years.
Your trees appear to be younger specimens of Pinus pinea or the Italian Stone Pine, based on the description on page 14 in Ritter. No other conifer in the book matches better.  Going to Wikipedia the description also seems to fit, in particular they mention &quot;...in youth it is a bushy globe...&quot;  There is also good information at Kew where I found this image, which looks to be very similar to what you observed.
Of course, if you can visit the location again you can check for needles in pairs, and orange-brown scaly bark.