Sarah Imeinu, the wife of Avraham Avinu and the matriarch of the Jewish nation, was niftar on the same day as Akeidas Yitzchak.  She is buried in the Cave of Machpela with Avraham Avinu, Yaakov, Leah, Yitzchak and Rivka, as well as Adam and Chava.

For more information: http://www.machpela.com