WOOD !! Rofl .... Well, that's what I look for. Since none of the lakes I fish have any major amount of water weeds, it seems the Black Crappie just use the same basic areas & wood cover that the White Crappie will use. They might do it a bit earlier, but sometimes they're found together (or in close proximity).
I want that wood to be on a bank protected from any current, and in water less than 10' deep. A pea gravel bank, old dock, pocket off the main line of the bank, deeper rock bank in between shallow mud banks, blowdowns coming off the shore into deeper water ... all have held spawning fish, at one time or another, on various different lakes I've fished. But, the ONE factor that seemed to always be present on any of these places, was wood cover of some kind. Didn't have to be as big as a tree, or even a stump, as I've caught good sized fish from nothing more than a handful of waterlogged twigs, that wouldn't cover a dinner plate.
... cp