Notes in Fallout 76 can be found scattered across Appalachia, and can contain scraps of lore, the stories of those who once lived in West Virginia, and various other information.
Transcript for Hallsey's Note
Holy crap! Those stupid soldiers left us a jackpot at the power plant.
There's all sorts of primo stuff we can scrap and plenty of supplies to go around. Round up the rest of the gang and get them over here right away. We're not carrying this stuff back on our own.
Where to find Hallsey's Note
At Monongah Power Plant, on the desk in the lobby entrance.