RD,
I was just throwing out possible explanations for the iron ball. Who know what the thing was as it has been blown to smithereens. However, a Civil War land mine it most likely was not.
It may indeed have been related to CW activity around Dardenelle, but with no existing evidence its all pure speculation at this point.
Pretty soon another unsuspecting Arkansan will unearth a CW projectile, they will panic, the bomb squad will be called, and another piece of history will be destroyed by the ignorant. That seems to be a common theme in this state these days.
BG