R.I. Gen. Laws § 21-20-1: Vegetables to be sold by weight.

It shall be unlawful for any person, firm, partnership, or corporation to sell at retail or offer to sell at retail any lima, fava, shell, wax, or green snap beans, peas, spinach, kale, dandelions, and potatoes, and any other vegetables of the commonly accepted staple classes as may be determined by the director of environmental management, in any other manner or measure other than by weight.