Back in 1967, Linda Ronstadt and the Stone Poneys had a hit with "Different Drum." The lyrics tell the story of a couple in the midst of breaking up because each person "travels to the beat of a different drum." Most people understood this reference at the time because Thoreau's words seemed to be everywhere in the 1960s. Especially with the movements of civil rights and environmentalism, his philosophies became even more relevant. Also in 1967, a U.S. postage stamp was released with his face on it, to celebrate the 150th anniversary of his birth. Henry was everywhere, and his quote about someone hearing and following the beat of a different drum was (and still is) quite popular.
On the other hand, Don McLean released a song in 1969 called "Castles in the Air." In it, the boy is breaking up with the girl because he's tired of her "castles in the air." "Castle walls just lead me to despair," he says. This seems to be a reference to Thoreau's "Conclusion" chapter of Walden: "If you have built castles in the air, your work need not be lost; that is where they should be. Now put the foundations under them." The trouble with the girlfriend in the song is that she never follows up on her plans, and her boyfriend grows too frustrated with her inactivity to stick around.
On the Dark Side of the Moon album by Pink Floyd, you'll find the song "Time." It includes the line: "Hanging on in quiet desperation is the English way." This seems to refer to Thoreau's quote, "The mass of men lead lives of quiet desperation." Pink Floyd's lyrics talk about the need to make the most of life and the time we have, otherwise "one day you find ten years have got behind you," and you have nothing to show for it. This is a dark song, focusing on the time people waste without even realizing it. Hopefully listeners understand that they have the ability to lift themselves up out of this "quiet desperation."
Otherwise: look for songs about a love of nature or the spirit of independent thought.