best cal / mag nute?

what's the best organic cal and/or mag nute(s)? i'm really asking for the natural item and not a brand.

Ummm crab and oyster shells and epsom salt. I have been collecting clam and mussel shells and crushing them as a cheap and very good soil ammendment. And i always add some epsom salt to my soil mix, but still have mag deficency. I foliar mag a lot.

If you are in flowering I would top dress and make a fast acting tea out of comfrey. Totally natural, grows like a weed. And it will supply some K while it's at it.

Almost everything has calcium in it. As far as the two together go with dolomite lime. It supplies cal and mag. You can pick up a 40lb bag for 5 bucks at lowes or Home Depot.

1 cup/ cu ft soil and you shouldn't see anymore defs. If that doesn't work like banana said, throw some Epsom salts in there, won't hurt anything.