Agent Anne Weaver was the head of the Science and Technology division of S.H.I.E.L.D. Academy, before HYDRA was discovered to be lurking within S.H.I.E.L.D. In "Seeds" she is seen meeting with Agent Coulson's team in order to help them locate the Atmospheric Moisture Freezing Device developed by one of the students at the academy. In "Turn, Turn, Turn" she also makes an appearance, warning Agent Simmons of S.H.I.E.L.D's compromise, telling her not to trust anyone.
It is presumed that she is either dead, missing, on the run, or a captive of HYDRA, due to her conversation with Agent Simmons being cut short by an explosion at her end.
It's also said in the episode "Afterlife", that Phil Coulson bribed her with cupcakes to let him have Fitz-Simmons on his team.