The mechanical and rheological properties of jammed packings of frictionless particles under shear strain remain not fully understood, even when the strain amplitude is very small and well below the yielding threshold. Systems above the jamming transition point are known to display two anomalous mechanical behaviors both with respect to the driving frequency and the strain amplitude. We study these behaviors using three rheological protocols: simple shear, oscillatory shear, and transient stress relaxation. Our results demonstrate that the mechanical responses are not simply described as a superposition of the two algebraic relaxations and instead exhibit rich nonlinear viscoelastic behavior both above and even below the jamming transition point. The mechanical and rheological properties of jammed packings of frictionless particles under shear strain remain not fully understood, even when the strain amplitude is very small and well below the yielding threshold. Systems above the jamming transition point are known to display two anomalous mechanical behaviors both with respect to the driving frequency and the strain amplitude. We study these behaviors using three rheological protocols: simple shear, oscillatory shear, and transient stress relaxation. Our results demonstrate that the mechanical responses are not simply described as a superposition of the two algebraic relaxations and instead exhibit rich nonlinear viscoelastic behavior both above and even below the jamming transition point.