The Boudin Sourdough Bread Company of San Francisco, specializes in its sourdough French Bread. They have been using the same 'Mother Dough' since 1849. The company claims to be the oldest business in San Francisco, with its founding back in the days of the California Gold Rush by an "Isadore Boudin, a Frenchman with gold fever who wound up in San Francisco in 1849 too poor to buy picks, pans, ponies and tents. Falling back on other skills, he baked traditional French bread nontraditionally, using a sourdough starter."
The company believes its mother dough to be so valuable that a few years ago when the company opened a new 30,000 square-foot bakery in San Diego, they "insured some Boudin sourdough starter for $1 million and flew it first-class for the opening of the bakery."
The company was purchased in 1993 by Specialty Food Corp. of Chicago, and now operates 30 restaurants in the Bay Area and 15 in other parts of the US.
The Los Angeles Times. (Record edition). Los Angeles, Calif.: Oct 15, 1998. pg. 10
The Los Angeles Times (Pre-1997 Fulltext). Los Angeles, Calif.: Dec 30, 1990. pg. 1