Described are very high molecular weight (e.g., over 2 million, such as 3-20 million g/mol) starch-based materials, and formulations including such, which can be spun in spunbond, melt blown, yarn, or similar processes. Even with such very high molecular weights, the formulations can be processed at commercial line speeds, with spinneret shear viscosities of 1000 sec−1, without onset of melt flow instability. The starch-based material can be blended with one or more thermoplastic materials having higher melt flow index value(s), which serve as a diluent and plasticizer, allowing the very viscous starch-based component to be spun under such conditions. The particular melt flow index characteristics of the thermoplastic diluent material can be selected based on what type of process is being used (e.g., spunbond, melt blown, yarn, etc.). The starch-based material may exhibit high shear sensitivity, strain hardening behavior, and/or very high critical shear stress (e.g., at least 125 kPa).