The present research work is focussed on the development of agro-waste-based bio-filler-reinforced polymer composites with reinforcement derived from three different plants sources and investigating its static and dynamic mechanical properties with strain rate and temperature variation. The chosen plant sources are wood, bamboo and coconut, derived from the stem and fruit part of the plant. The reinforcing fillers are subjected to alkali treatment to make its surface rougher and suppress moisture absorption. A specific grade epoxy composite is prepared using five different weight fractions of all three micro size treated particle fillers. The composite specimens are tested in uniaxial tension loading with varying crosshead speeds to evaluate its effect on strength and stiffness of bio-composite samples. Moreover, the linear elastic fracture mechanics is applied to reveal the fracture toughness value and mechanism of fracture initiation and propagation. The glass transition temperature and damping factor of the produced reinforced plastic material are evaluated with dynamic mechanical analysis over a spectrum of temperature from RT to 150 degrees C. It is observed from the result that Young's modulus value increased by approximately 16% as filler type is changed from bamboo to wood. For the best static mechanical properties, coir and wood filler are found to be the most suitable amongst all three filler materials. Moreover, the glass transition temperature was observed to be increased as filler type changes from stem kind to fruit kind for most of the filler loading.