That's a great point Cartie. Do we know when she made the mushroom brownies? Potentially before the dehydrator purchase. Regardless, you could argue that she was experimenting with mushroom powder, what it tastes like it recipes without mushroom, whether it was detectable in any way. With regular, edible mushrooms of course because she wouldn't want her kids sick.
If she did not have a dehydrator until April 28th, yet was still able to dehydrate mushrooms, then one could say that there was a reason why she chose to buy one then. Right after having visited a location known to have...