I'd recommend interacting with the US Department of Labor (http://www.dol.gov/dol/topic/youthlabor/agerequirements.htm) and the Washington State Department of Labor & Industries (http://www.lni.wa.gov/workplacerights/teenworkers/). The 2013 Washington minimum wage is $9.19. Washington's minimum wage applies to workers in both agriculture and non-agricultural jobs, although 14- and 15-year-olds may be paid 85% of the minimum wage ($7.81). Whether the children are truly volunteers or not is a question of fact that skillful lawyers might argue about for an extremely long time.
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