“Scarborough Fair” has been around for centuries, but it was popularized in the 1960s by Paul Simon’s arrangement of it for Simon and Garfunkel. Even without all their tricky layers of guitar parts, it’s a challenging tune, as it involves several chords and you never stay on one chord for long.
As a song for learning to switch between minor and major chords, it can’t be beat, and of course it is a beautiful song. So here it is. It’s in 3/4, so take the above bass/strum patterns on E and A minor and lop off the fourth beat.