I found the following quote, attributed to author Herb Caen.
I have a memory like an elephant. I remember every elephant I've ever met.
However, my efforts to identify the source of this quote via Google has come up empty. The search results push me toward quote collections that attribute this quote to him without citation.
Interestingly, Wikiquote does not attribute this quote to him.
Is there a publication or book citation for this quote? Barring that, an interview or biographical article which provides conversational context for when he made this statement?