Mona Lisa.

People In his book, American Story, NBC journalist Bob Dotson meets people who've done extraordinary things. In an extract on Today's website he interviews Florence Thompson, an image of whom became iconic during the great depression:

"I found a trailer camp on the site of the old migrant camp in Modesto, California. During the Depression it was just one of many stops on that endless road. It was still home to Florence Thompson, the Mona Lisa of the 1930s, the migrant woman whose picture haunted the nation. Florence Thompson — no, you probably wouldn’t recognize the name, but few can forget her face from Dorothea Lange’s iconic 1936 photograph Migrant Mother. Florence Thompson was 27 years old when the Depression began. She had five children, was pregnant with another — and her husband had just died."

This is the photograph and the Wikipedia has some background.  The most poignant part of the interview is when Dotson asks her if she ever lost hope.  She says she never did.