The conduction electron spin resonance (CESR) linewidth of polycrystalline pure silver foils and some of its dilute alloys have been measured from 4.2 to 25K at 40 MHz, 9.27 and 20.9 GHz. The spin-flip scattering cross sections are given for copper, palladium, platinum and gold in silver; these are found to be frequency independent. There is however, a frequency-dependent contribution to the linewidth for all purities which is found to be linearly dependent upon frequency and inversely proportional to the sample thickness. It is suggested that this frequency- and thickness-dependent term is dominated by surface roughness and, as such, is due to high-angle scattering at the surface. The mechanism provides rapid mixing of states on the Fermi surface necks, those with large spin-orbit coupling with the very nearly free electron states on the 'belly'. With careful removal of the residual linewidth contributions caused by impurities, defects and the surface, the intrinsic temperature-dependent portion of the CESR linewidth has been extracted. At very low temperatures this varies as exp(-T/120) which suggests once again the importance of high-angle scattering brought about by the few remaining high-energy phonons found at these temperatures. As the temperature is increased, normal spin-phonon scattering of the 'belly' electrons start to take over, thus overriding the significance of the high-angle scattering leading then to a T4 dependence, in approximate accordance with expectations from phonon scattering theory.