Large scale rice production in the state of Arkansas became a significant industry in the late 19th/early 20th century with its wide scale propagation within the state by entrepreneur W.H. Fuller around 1896.
A cubic yard of sand approximately weighs 1.3 tons, 2,600 pounds ,or (for non imperial people) 1,179.34 kilograms.
A cubic yard of dry gravel will weight 2500 to 2800 lbs depending on the size. If it is wet add five hundred pounds per c/y. So a ton can be quite a bit less than a cubic yard. You can ask the person or business delivering the gravel.