Occasionally I come across this site when I am researching a food topic, it has some great stuff and offers loads of material and sources for historical research. http://www.foodtimeline.org/index.html
This is their section on sourdough in California. I see that they quote Ed Wood here:http://www.foodtimeline.org/foodbreads.html#sourdough
Once you have read that part scroll up or down and get sucked into a lot more interesting baking history. Sometimes the site seems to only focus on North American History, but there is other cultural history here, so If you have your own research on local breads to contribute, this might be a good place to present it.
Enjoy... but keep this quote in mind.
"The lesson here is never completely trust the first source you use when researching history, even if it is a standard reference volume. Sometimes it takes a little work to separate the legends from the facts. "
Also I really enjoyed this site I found on Morpeth Sourdough in Austrailia. With their long history it is good to see they still are making bread right! http://www.morpethsourdough.com.au/Morpeth_main.php
You really are what you eat, so eat wisely...