Cows
I was told once that a landscape is more likely to sell with a cow in. And, more likely a cow than a sheep or a horse. Humans seem to have an affinity for cows. There is something soothing about looking at cows, and painting them is soothing too. When painting them in the field, you need to stand far away to capture the bucolic scene, because if they see you there, they will just stare at you.