Some first time heard songs that blew my mind...

Like A Rolling Stone
Now That The Buffalo's Gone
Blowin' In The Wind (first heard it by PPM)
Hey Joe (Hendrix)
Hey Jude
My Country Tis of thy People You're Dying
Piney Wood Hills
Clouds
Michael From Mountains
Gates of Eden
Mr Tambourine Man
The Night They Drove Old Dixie Down
Roads To Moscow
Love Chronicles
Sounds of Silence

And that's just scratching the surface...