The increasing use of composites reinforced with vegetable fibers in the industrial field poses a serious problem of the reliability of the structures produced. For us, this credibility can be ensured when developing the composite, by a judicious choice of matrix and reinforcement, a choice leading to obtaining a material having acceptable mechanical and physicochemical characteristics. The main objective of this study is to characterize a composite material with a clay matrix reinforced with coconut and palm nut fibers. To achieve this objective, we first opted for the implementation of this composite by contact molding, at different fiber percentages (2.5%, 5%, 7.5%, and 10%), and we then subjected our specimens to mechanical tests (three-point bending and compression). The mechanical characterization allowed us to have a Young’s modulus in compression varying between 63.82 and 68.82 MPa for palm nut fibers and from 68.28 to 74.43 MPa for coconut fibers (this allows us to note that our coconut fibers make the material rigid in compression), and a Young’s modulus in bending varying between 5.71 and 6.51 MPa for palm nut fibers and from 6.50 to 6.525 MPa for coconut fibers (this allows us to see that our coconut fibers make the material rigid in bending). The results also show that the rate of water absorption of the composite increases with the increase in the fiber content, which is explained in particular by the fact that the fibers of plant origin are hydrophilic and have a porous character; therefore, they absorb water. This study also shows that there is a reduction in the density of the fiber composite with increasing fiber content.