I think they were the "California Angels" for most of their history. However, that's kind of generic. I don't know of many Angels fans up here.
I drove by once. Wasn't quite sure where it was in relation to the border. And yeah they have a Petaluma mailing address. However, I've learned that mailing addresses can often be a fiction, especially when there's no official name for an unincorporated area. Once I wanted to buy a house, but it was technically in Richmond, CA. The seller advertised it as El Cerrito, which doesn't quite have the same negative reputation as Richmond. Then the title company came back with that, and as an incorrect material fact we could ask for our deposit back. And even the title company researched it, the owner was upset and said she couldn't possibly be living in Richmond, although she did offer to reduce the price. Later we found that she lowered the price even more since it was a bad market.
I live near Tilden Regional Park. It's almost completely within Contra Costa County, and all of the major attractions and in my county. The merry go round tickets say Berkeley and apparently that's what they use as a mailing address. As far as I can tell, the USPS is very lenient on this as long as they can figure out where to get something delivered. The house I mentioned I didn't buy apparently got its mail just fine even though the owner kept on using the incorrect city and zip code.