On this most auspicious day, 163 years ago, John Marshall discovered gold in a mill race in Coloma, California, and kicked off one crazed gold rush after another to fill California with folks aiming to get rich quick. Luckily, most of them, once they didn't get rich quick, figured out California wasn't a bad place, and ended up staying. Hopefully you celebrated the day via Talk Like a Grizzled Prospector day.
Andersen Model Kits, and their adobe structures. The adobes are a bit too New Mexico for a good California layout, but their Candelario Miramontes Adobe is a perfect match for what the typical Mexican era rancho would have looked like. It's too primitive to be Monterey style, but that's what the early Europeans families typically had in the early 19th century. You'd be hard-pressed to find one next to a California railroad (just because the land before the Gold Rush was so sparsely populated), but it's still authentic.