On this page of the Assassin's Creed Valhalla guide, you will find a detailed walkthrough for the Lamb Chops side quest.
Rewards: 1,200 XP.
In the place marked on the image above, you will meet a man who is grieving over the loss of a family heirloom - a brooch. It must have been swallowed by one of his sheep.
The man wants her back, but without hurting any of the sheep. Take a bundle of hay and place it near the sheep.
Now you need to extract the brooch from the feces - you will find it in the place marked on the above picture. Talk to the man and return the family heirloom to complete this task.