Our group has been investigating the use of Shearwave Dispersion Ultrasound Vibrometry (SDUV) for quantifying viscoelasticity of the myocardium. The primary aim of this study is the design and testing of viscoelastic materials suitable for validation of the Lamb wave model in the heart. The Lamb wave SDUV method was used to measure shear wave velocity dispersion of gelatin and urethane rubber plates in the range 40-500 Hz and estimate the material properties. A finite element model (FEM) of a viscoelastic plate submerged in water was used to study the appropriateness of the Lamb wave dispersion equations. An embedded sphere method was used as an independent measurement of viscoelasticity. The FEM wave velocity dispersion data were in excellent agreement with the theoretical predictions. Elasticity and viscosity of urethane and gelatin obtained using the Lamb wave SDUV and embedded sphere methods agree within one standard deviation.