Connie,
The 'Austrian Winter Peas' that I've seen advertized(and I planted them one year) for planting in wildlife food plots do not resemble blackeye/pinkeye/cowpeas in any respect - they are, for all intents and purposes, an 'unimproved' 'English pea'/snowpea type(Pisum sativum, maybe?) pod & seed - the little round green peas.
I would suppose that the leaves and pods/peas would be edible - I just don't know how tasty.

Here is a link that might be useful: Austrian winterpea

It's mid-May here. My Austrian Winter Peas have grown 6-7 feet tall up my 6 ft chainlink fence. They flowered cute little purple flower which gave way to mini looking snow pea pods with seeds the size of pin heads at this time of the season.

I ate one today and it tasted like a tender, fresh garden pea; the flower, stems and leaves taste the same at this time. It will be interesting to see the taste as the summer progresses and they age.

I grew about 40 row feet of Austrian Winter two years ago. You can use the sprouts and shoots as greens, the young pods as snow peas, the green shelling stage is perfectly edible but a little more starchy than traditional green peas. The dry pea is a yellow soup pea -- I ground mine into pea flour and used small quantities in bread baking. To my knowledge, there isn't a practical way to split and dehull dry peas at home.