Models of surface and subsurface microstructure were created and Monte Carlo light scattering simulations were performed to generate accurate surface reflectance functions. Iridescent hummingbird feathers and paper sheets were studied in order to obtain detailed information about their morphology. It is known that measured spectral response curves of hummingbird feathers deviate from those of corresponding ideal thin films. The reflectance functions generated showed similar deviations. For paper, a simple layered model was constructed and the resulting reflectance functions compared favorably with theoretical calculations used to determine diffuse reflectance. Measurements of the spatial scattering of light from paper revealed that a significant amount of back scatter was present in some cases and that a certain amount of anisotropy was also present. By constructing models of the paper web and its coatings, these effects were reproduced and possible origins of these effects were indicated.