"Yesterday" by The Beatles
The lyrics include the line:
*"Yesterday, all my troubles seemed so far away..."*
Here, "Yesterday" is the subordinating conjunction, introducing a dependent clause (the entire line) that describes the past. The independent clause (not shown here) would go on to explain how the speaker's perspective has changed.
Here's a poem with a subordinating conjunction:
*"The Road Not Taken" by Robert Frost*
This poem features the famous lines:
*"Two roads diverged in a yellow wood,
And sorry I could not travel both
And be one traveler, long I stood
And looked down one as far as I could
To where it bent in the undergrowth;"*
The line, "And sorry I could not travel both" uses the subordinating conjunction "and" to introduce a dependent clause that explains the speaker's regret.
Let me know if you'd like examples of other songs or poems with different subordinating conjunctions!