Its perfectly normal for a pup to do this. Try and clear up thoroughly before he gets the chance to feast and this should break the habit. Also, if he has accidents indoors dont tell him off as he will eat it so that you dont find it!
It could also be that hes hungry so make sure that you are feeding the right amounts. I would be concentrating my efforts on eliminating those 'cowpat' poos rather than worrying about him eating them. Try and work out why hes doing them as if they are quite runny it might be that for whatever reason he is not taking the goodness out of his feed and is left feeling hungry and therefore eating his poo.
Nature Diet food produces a good hard poo.
Good Luck
My goal in life is to be as good as my dog already thinks I am