Regarding " looking for straight up organic source of camg," do you really mean that you want only use products that are "organic" (vs. inorganic)? Or do you really mean to say you are interested in finding supplements that fit within what most would consider organic growing methods? Or are you really seeking only "natural" products?"
I don' see how any pure (not further supplemented) calmag supplement, itself, can be "organic." There simply should be no organic, carbon-baesd molecules at all. Similarly, epsom salts (MgSO4) and the rock and mineral powders people mix into soil are not organic, rather are inorganic. But all of these things can be fully "natural."
Among the many definitions of and certification programs designating "organic," I presume most allow use of natural mineral supplements as part of "organic" growing methods. Maybe, check out
http://www.omri.org.