its a form of pay chit for migrant labors -- as they gathered tomatos the workers handed the "bossman" the filled bucket --in exchange they got a token --at the end of the job-- the tokens were "cashed out" for money -- however until the "job" was through however they could only be used to buy company goods via the company store / supply outfit (often at highly inflated prices) by using tokens the migants were forced to buy at the company store or do without --as local stores would not accept the tokens as cash
and not having cash they could not just quit the job and walk away no matter how badly they were treated (because they would be broke until the job was done )-- because only when the job was done and they were through with you--laborwize-- were the chits redeemed for cash.
by passing out chits --you could track who was working hard and who was slacking the easy way -- since it cost so many chits a day to pay for room and board -- if you were too slack you did not have enough chits to pay your way -- so maybe nothing to eat for you or maybe sleep outside--(great way to "motivate" slacker type workers) --by using these chits no other bookkeeping needed to be done -- so many chits a day for room and board -- and other company store / supply items were "sold" for chits as well -- any extra ones got cashed out at the end of the "job" for cash money -- simple , brutal and effective