The blacks usually start popping about the last week in March / first week in April here in Athens County. The soil temp and precipitation seem to be the determining factors.

My strategy for finding mushrooms is geared more towards specific trees. I find the vast majority of blacks around poplar trees and the yellow and greys near ash and elm trees. A dying elm tree with the bark just starting to loosen is usually golden. Supposedly the spore are contained inside the tree bark and the flaking off releases them. I pretty much just walk from tree to tree and look down.

Some of the old timers in this area believe that mushrooms are on a 7 year cycle in that every 7 years there will be a bumper crop. I can't say there's any science behind it but since I started paying attention many years ago they seem to be right.