Abstract: In this talk, I will explain how one obtains quasimodular forms from generating functions of stationary descendent Gromov-Witten (GW) invariants of an elliptic curve. As an application, one can compute all of the ways to express the discriminant modular form in terms of these generating functions. This provides a possible strategy to resolve a conjecture of Lehmer that says the Ramanujan tau function never vanishes.