The Cows Collection is a collection. You can acquire the items when a neighbor posts a Cow Collection item to their News feed. You can also acquire the items when harvesting from Cows, either your own farm and Dairy Farm, or that of a neighbor.

Cow Bell	Milking Bucket	Milking Stool	Milk Bottle	More Cowbell
Common	Common	Common	Uncommon	Rare

Collection Level	Coins	XP	Rewards
Level 1	500 coins	50 XP	Fuel
Level 2	1,000 coins	100 XP	Cow Topiary in Bloom
Level 3	1,500 coins	150 XP	Rainbow Cow
Level 4	2,000 coins	200 XP	Fuel
Level 5	2,500 coins	250 XP	Fuel