Gleaning

Gleaning is the act of collecting leftover crops from farmers' fields after they have been commercially harvested or on fields where it is not economically profitable to harvest. Some ancient cultures promoted gleaning as an early form of a welfare system.

from Wikipedia, http://en.wikipedia.org/wiki/Gleaning ,

biblical references include the idea of purposely incomplete harvesting as a gift for the poor, the ill and the rejected. art references suggest that gleaners (freegans avant la lettre?) were once a common sight.

of course: someone has done a gmap glean app:

http://www.goglean.org/