Les glaneurs et la glaneuse (2000), translated literally as "the gleaners and the female gleaner", is a French documentary film by Agnès Varda that features various kinds of gleaning. It is a great example of the beauty, "waste" and social disregard of human potential.
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Les Glaneurs et la Glaneuse a documentary by Agnès Varda - myskreen.com 
There is a great scene towards the end of the documentary (#DigOutClip?) about a street teacher / maths professor from the Banlieue.
Les Glaneurs was entered into competition at the 2000 Cannes Film Festival ("Official Selection 2000"), and later went on to win awards around the world. In a 2014 Sight and Sound poll, film critics voted The Gleaners and I the eighth best documentary film of all time - wikipedia