Hi Steve!Glad you could join us! 
AM sent me this post from an historical food list some time ago. It seems to answer most, if not all of your question.
Hope this helps!
Gwen
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AM said :"You want stuff out of the pea/lentil/fava/garbanzo family, nitrogen fixers, vetch leaves, etc., not the fasiolis i.e. bean/string bean/lima bean/scarlet runner bean/etc family."
Someone named "Bear" said: "Blackeyed peas are Vigna unguiculata and are of Old World origin (probably India with variants in China and Africa). Catjangs, cowpeas, and yard-long beans are all variants. The Italians lump them together with the New World Phaseolus, but they apparently were known and eaten (as food of the poor) in Classical Antiquity (see Pliny).
If you look at the language, peas, lentils, favas and grabanzos are liguistically separate from phaseolus. The confusion comes because the Vigna and the New World beans were lumped together as fagiola (or fasioli) and then the term Phaseolus was taken taxonomically for the New World beans. Because the Vigna are tied linguistically to the modern variant of phaseolus, they are probably the phaseolus of the Romans.
I refer you to Annibale Carracci's The Bean Eater for visual evidence of black-eyed peas being eaten in period. (I think this is 16th C.)
While Platina gives some recipes specifically for phaseolus (and remembering he predates Columbus and most taxonomic efforts), it is very likely that black-eyed peas would not be found much outside of peasant dining."
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