The free-produce movement was an international boycott of goods produced by slave labor. It was used by the abolitionist movement as a non-violent way for individuals, including the disenfranchised, to fight slavery.[1]
In this context, free signifies "not enslaved" (i.e. "having the legal and political rights of a citizen"[2]). It does not mean "without cost". Similarly, "produce" does not mean just fruits and vegetables, but a wide variety of products made by slaves, including clothing, dry goods, shoes, soaps, ice cream, and candy.[3]