In addition to McCartney's "Yesterday," there's also an older song (from the first half of the 20th C.) titled "Yesterdays."

The above had music by Jerome Kern.

Eric Bogle - Scraps of Paper
Paul Simon - Bookends, Part 2 ("preserve your memories, they're all that's left you"
Remember - Nilsson ("Long Ago, Far Away...")
The "Gigi" I Remember It Well was actually a rewrite. Alan Jay Lerner wrote a similar song with the same title with Kurt Weill for LOVE LIFE in the late 1940s', available on one of Ben Bagley's Painted Smiles collections.