These doggie chews are made only of cow ears, sources from cattle that have been fed exclusively with grass and grown in free range style of livestock farming. (mypetneedsthat.com)
If you want to go minimalist with your treat selection, consider whole cow ears. (heavy.com)
For cow ears, pig ears, and rawhide chews, the best online source I have found is Raw Feeding Miami. (drjensdogblog.com)