Time to go back to the old 'Songs recently featured on Glee' well.
Gotye - Somebody That I Used To Know
Florence + The Machine - Shake It Out
Kelly Clarkson - Cry
Edit: the above posted before I was aware of the Walden hint.
Don Henley has been a vocal supporter of the Walden Woods project:
So if the clue is that direct, we're talking the Eagles or Don Henley.
Don Henley 01:
The Boys of Summer
The End of the Innocence