Fast growing plants or biomass wastes can be used as affordable and environmentally sustainable alternatives to synthetic insulation materials. The aim of this study was to investigate the mechanical properties (tensile strength and Young’s modulus) of natural fiber reinforced polymer composites as potential building materials. As a natural fiber, Bermuda grass seeds, conifer cones and pinecones are selected. The fundamental processes to develop nanofiber reinforced resin by processing agricultural waste fibers into nanocellulose is also investigated. Tensile tests are conducted to define stress/strain relationship. SEM tests are conducted to evaluate the surface topologies after fracture. The tensile fracture surfaces of composites were investigated. With the addition of Bermuda fibers, the stiffness of the vinyl ester sample was observed to increase by 624.2% compared to neat vinyl ester sample. With the addition of nanocellulose fibers, the stiffness of the composite was observed to increase by 53.3% compared to neat vinyl ester sample.