A significant byproduct of almond fruit industry, hard almond shells, was considered as a supplement material in particleboards for contributing to the circular economy goal with a higher added value product. The envisioned particle boards were not only for furniture but also construction regarding insulation. Accordingly, industry unspecific boards were produced. Almond shells were obtained from industry and ground into particles ranging from 0.4 to 3.4 mm. Those particles were mixed with black pine particles in different mass ratios to produce particleboards. The production included chemical and physical processes. Generated particleboards were subjected to specific physical and mechanical tests. Physical properties, such as density, thickness swelling, and water absorption, were determined. Mechanical properties, including deflection, elasticity modulus, bending stress, and maximum force before failure values were also measured and calculated. Boards with different densities were subjected to same mechanical and physical tests. The results show that an increase in almond shell particle amount in the particleboard makes the board more brittle and rigid. The physical tests show less thickness swelling and water absorption with increasing amount of almond shell particles. Therefore, almond shell particles may be more favorable for indoor decoration or insulation instead of furniture. Board density has a marginal effect on mechanical behavior, and it should be one of the determinant factors for feasibility of the boards in different utilization scenarios.