There is actually a concise, but sadly rather short, description of the varieties of Greek bread on Wikipedia. Apparently, according to the article, Solon ordained that leavened bread should be reserved for special occasion, and bread was leavened with a yeast coming from wine fermentation.
Another random factoid from my memory is that in Ancient Greece: A Political, Social and Cultural History, the authors alledge that the ancient Greeks did not like the taste of butter. My first question was, "how would you know?"
- I apologize for my lack of citation but I am doing this from memory. I will hopefully come back and add the section numbers at some point.