A monitoring device for monitoring crop yield, the monitoring device comprising: a mounting structure configured to be mounted to a housing of a grain elevator of an agricultural work machine, the mounting structure comprising at least one aperture formed therein; a fulcrum assembly arranged on the mounting structure, the fulcrum assembly having a pivot point; a material engagement member at least partially disposed within the aperture, the material engagement member being pivotal with respect to the mounting structure about the pivot point of the fulcrum assembly, the material engagement member having a first end and a second end opposite of the first end; a rotational sensor coupled to the fulcrum assembly, wherein the at least one rotational sensor is configured to detect spatial movement or position of the material engagement member and output a signal corresponding to a rotational magnitude of displacement of the first end or second end of the material engagement member relative to the pivot point, wherein the displacement is induced by the exertion of a force generated by an agricultural material engaged with a surface of at least one of the first or the second end of the material engagement member, and wherein the displacement of the first end or second end is proportional to a degree of pivotal movement of the material engagement member about a pivot point axis; and a processing device coupled to the rotational sensor and configured to determine a mass flow rate of the agricultural material based on the detected rotational magnitude of the displacement of the first end or second end, and wherein an aggregate crop yield is determined based on the mass flow rate. a mounting structure configured to be mounted to a housing of a grain elevator of an agricultural work machine, the mounting structure comprising at least one aperture formed therein; a fulcrum assembly arranged on the mounting structure, the fulcrum assembly having a pivot point; a material engagement member at least partially disposed within the aperture, the material engagement member being pivotal with respect to the mounting structure about the pivot point of the fulcrum assembly, the material engagement member having a first end and a second end opposite of the first end; a rotational sensor coupled to the fulcrum assembly, wherein the at least one rotational sensor is configured to detect spatial movement or position of the material engagement member and output a signal corresponding to a rotational magnitude of displacement of the first end or second end of the material engagement member relative to the pivot point, wherein the displacement is induced by the exertion of a force generated by an agricultural material engaged with a surface of at least one of the first or the second end of the material engagement member, and wherein the displacement of the first end or second end is proportional to a degree of pivotal movement of the material engagement member about a pivot point axis; and a processing device coupled to the rotational sensor and configured to determine a mass flow rate of the agricultural material based on the detected rotational magnitude of the displacement of the first end or second end, and wherein an aggregate crop yield is determined based on the mass flow rate.