FarmVille's single biggest expansion was English Countryside, released around March 2011.
English Countryside gave players an entirely separate farm plot with its own theme: new crops, animals, buildings, and decorations styled after the English countryside rather than the original game's American-farm aesthetic. Importantly, progress carried over — a player's coins, Farm Cash, gift inventory, farm size, and overall level of achievement all transferred into the new expansion rather than starting from zero.
The expansion later received its own follow-up event content, including a "Return to English Countryside" quest line, showing that Zynga treated it as an ongoing second setting for the game rather than a one-time addition.