Abandoned Mill
The farmland you are travelling through shows signs of abandonment. The crops grow in clumps and patches here and there, birds eat the overripe grains and the root crops appear weedy and tough - a successful Nature check (DC 13) reveals that these plants probably seeded themselves and have probably done so season after season.
The ground rises toward a hill not far off from the abandoned fields. Atop the hill is a derelict windmill - the sailcloth is long gone, but an occasional wind gust still catches the sails. If the party approaches the mill they will hear the distinct sound of stone grinding on stone when one of these gusts hits. The inner workings of the mill are still in fair condition and the gusts move the mill stone a few inches every time.
Sacks of rotted and rotting flour are stacked in the lower levels of the mill. The roof is in disrepair, letting in rain and causing the upper level floorboards to be mostly rotted. A successful Perception DC 15 will reveal the state of the upper floor - the second floor (accessed by a ladder) can hold up to 120 pounds - if any more weight is added, the floor will collapse dealing 1d6 falling damage to whoever was on the floor and 1d10 bludgeoning damage to everyone underneath (Acrobatics/Dex save DC 15 for half damage).
A long forgotten wooden box is also on the second floor. The box is locked and the lock is badly rusted (DC 20 to unlock, or AC 10, 3HP to smash). It will tumble down with the rest of the floor if it collapses. Inside is a leather bound ledger listing names, dates, weights and types of grain delivered for milling and a small bag of coins (20cp, 15sp & 3gp)
Seems like a good opportunity to hide an adventure hook with Thieves Cant.