D.W. Hunter claims the companies conspired to deny Harrington was a Quaker Oats employee ... but continued to exploit her image for more than 60 years without paying up.
Harrington was selected for the role because of her pancake recipe -- which they recreated for the grocery store ... but her family believes racial exploitation was involved in the deal.
They claim Harrington was talked out of using a lawyer -- exploiting her lack of education so the company wouldn't have to pay for her recipe.
source: tmz.com