The Cow Pasture produces milk, and is almost as crucial to gameplay in Castleville Legends as the Oat Field. You'll be doing a LOT of dairy farming in this game, especially at the lower levels. But even as you level up, there's generally a lot of demands for dairy products, and only a portion of them will be able to be met by buying from the Sea Trading market.
To find out more about milk specifically, such as its pricing and the recipes in which it's used, check out the page about milk.
Available at level:
First: 375 royal coin, 30 crowns thereafter
Time to build after purchase:
Maximum number per kingdom: