I had some cultures from here:
https://sourdo.com/
Ed was a pathologist working in Saudi Arabia and started collecting some of the oldest cultures in the world. I had the original San Francisco culture and the Austrian culture from a bakery that opened in 1795.
Growing up in the Bay Area I was always a fanatic for good sourdough. A slice of Extra Sourdough with some hard chilled butter is still one of my favorite things.