In Wisconsin, especially on the Root River Trail and the Glacial Drumlin Trail, the benches seemed to be placed as part of an Eagle Scout Project or by BSA Troop 41 (I hope I remembered the number right--they did a lot of them). Good going scouts!
In western Wisconsin, few benches featured commemorations, and many were quite rudimentary.
On the Minnesota trails there have not been quite as many benches, until today. The bench pictured above is one of at least a half dozen benches in memory of Mark A. Hanson. My quick internet searching has not revealed who he was, but obviously someone wanted to make sure he was remembered.