The cache of Fleraud is quite difficult to find in the game Kingdom Come Deliverance. It is located in the property of his father, which is the farm along the river, near the wooden bridge.
This is the indication quickly given by the villagers. But it remains to spot it on the ground which is not a small matter.
Then you have to go to the end of the garden, on the other side of the fence. And there will be a pile of stones.