"She was unknown then, so I was able to spend a lot of time shooting her," photographer Clark recalled in a 1999 interview with Digital Journalist. "We'd go out to Griffith Park and she'd read poetry. I sent several rolls to LIFE in New York, but they wired back, 'Who the hell is Marilyn Monroe?'" It would not be long before the whole world would know her name. (
See more photos from this shoot.)