Speak of "Ievan Polkka"... Tom Paxton's song, "Jennifer's Rabbit", has exactly the same chord progression to it. Actually, the melody to "Jennifer's Rabbit" strongly resembles that of "Ievan Polkka". And that song isn't a sad one, too.
I think Tom Paxton wrote quite a few songs in minor key, like "Bobbitt" and "Lyndon Johnson Told the Nation". There are extremely sad ones, though, like "On the Road from Srebrenica", but most are not. On the contrary, most of Tom's sadder songs are in major key, like "Last Thing on My Mind" and "Can't Help But Wonder".
Speak of "Runaway" - doesn't that song switch to a major key in the middle? (From I'm a-walkin' in the rain... to the chorus) I like the Traveling Wilburys' version.