I don't think this one is much of a food source but deer do eat the rubbing shreds of cedar trees.
I watched and filmed bucks in Iowa approach a huge cedar rub and they began working it. Then I watched them pick at the shreds and eat it.
I saw Barry Wensel at the outdoor show in Pgh last weekend and I asked him if he'd ever seen that behavior in Iowa and he said that he had seen it.
Huge cedar rubs are very common in Iowa and I asked Barry if those rubs are scent marking or are they a result of bucks making shreds to eat? Barry said he feels they are both a scent mark and a minor food source.
Which makes me wonder how many other species of trees we see rubbed also have the shreds eaten. Could be what happens with pokeweed rubs. I have grown sunflower plots and when the plants were long picked clean, with nothing more than dead stalks 6 feet high, I watched bucks rub the stalk and pick at the shreds.