Does anyone have the FakeBook published by Hal Leonard? I don't.
But SheetMusicPlus says that The Happy Farmer is included in the Hal Leonard Fakebook.

Just came from checking that great digital storehouse of classical sheet music, the Petrucci Music Library.

What they have, under Robert Schumann, is ... nothing with lyrics.

They have instrumental transcriptions galore, though, in addition to Schumann's own piano-solo version from his Opus 68.

The United State sheet-music adaptation from about one hundred years ago, in which the piano accompanies an instrumental obbligato for flute, violin, or cello,
is titled "The Merry Peasant," for what it's worth.