Morphine. Morphine is an alkalois derived from the sap of papaverum somniferum - the common poppy. Not only is it natural, it is the gold standard against which other narcotics are measured. The poppy actually produces many other narcotics. Only a few narcotics are synthetic.
Not Sure. If you're asking if there is a non-narcotic substance as potent and effective as a narcotic for pain control, I'm not aware of any. But, there are internet blogs offering anecdotal evidence for such substances. They can't be relied upon for validity or efficacy.