John, good comments, thanks.
The relative humidity on top of the stack is 67%, and sometimes over 70%. I put a dehumidifier next to the stack and it is displaying 75%. Based on your comments and from reading more, the dehumidifier is off for now.
That level of humidity seems excessive for the tools, so tenting off the wet wood may be a better humidity control method.
I cut a piece for oven drying, but have to get an accurate scale first.
The tree stump was oozing water, so your estimate of 90% MC seems right.
Here is a pic of the wood stacked and stickered in the shop:
Black Walnut Pile Dec 2020.jpg
We may try and reorganize the stack, with the very best pieces at the bottom.
Jim