I found a very interesting resource online that mentions "cum panis": a book from 1872 called An English grammar and reading book for lower forms in classical schools. It lists two words in its glossary that come from "cum panis":
companion: a sharer of food, a comrade, fellow-traveller, partner
company: association, a number of partners
Now I'm thinking of looking more into Google books because you can download that one and others for free. Very cool.