It seems to me you are going about this the wrong way. You are thinking about the vast body of folk songs, when you ought to be thinking about the student.

What's she like? Energetic and lively? Solemn and aloof? Interested in causes? How sexually sophisticated is she? How well will she grasp the one million folk songs about a young woman betrayed by a philanderer?

And her voice - is it light and quick or dark and rich? Is she sassy or demure?

However that goes, I suggest taking a look at Contemplator's site for above-average songs.