A thermoplastic starch composition acquired from compounding a mixture comprising starch-containing agricultural byproducts in 45 to 70% by weight of total composition, the agricultural byproducts having a starch content less than 50% dry weight; thermoplastic synthetic polymer in 25 to 50% by weight of total composition; plasticizer in 1 to 10% by weight of total composition; and coupling agent in 1 to 5% by weight of total composition; the compounding performed at a first temperature which is higher than room temperature.