"Cornucopia: A sourcebook of edible plants" by stephen facciola is quite a tome of knowledge. There's another book that my friend Eric Toensmeier (co-author of Edible Forest Gardens + Perennial Vegetables) uses, it's really old but very complete -- I'll check with him what it is.
More interesting to me than a straight 'master-list' would be bio-region specific species lists that draw information from all the growers, hobbyists, scientist, and fruit-geeks in a given area. Lots and lots of this information can be collected from the back issues of Pomona and the archives of this listserv... and collaborative internet technology is just reaching the stage where we can effectively put together such a project.
I'm working on building the platform for such a project this winter and will keep the NAFEX community posted. Anybody interested in helping out?
I
am not a LEARNED neafexer by any stretch, but I wonder if the problem
is that there hasn't been a comprehensive survey of edible plants? I
mean do we even know all the plants there are out there? Some plants
may have only small parts that are edible (like saffron crocus). Some
become edible after processing (leeching bletting. ect.). What do you
call edible (regular food plants, starvation food, medicinals)? There
would just be to many factors involved in this evaluation. I wonder if
anyone could give a firm number to this question.