Just to be clear on what an Aunt is: An aunt is a person who is the sister or sister-in-law of a parent. Aunts are second-degree relatives and share 25% genetic overlap when they are the full sister of the parent. A half-aunt is a half-sister of one's parent and is a third-degree relative with 12.5% genetic overlap. If the aunt is a sister-in-law, direct genetic overlap will typically be less than 12.5%, as this person usually entered the family through marriage.
A grand-aunt (sometimes called a great-aunt) is the sister or sister-in-law of a grandparent. <Wikipedia> Now that we are clear: The definition is provided to give you an idea of how important it is to interview your Aunt(s). Whether she be your parent(s) sister, or the sister of your grandmother. She may have a wealth of information to share with you, so do your project a favor and locate all of your Aunts and set each one of them up for an interview.
If you have multiple Aunts in one family such as your mother's 4 sisters, interview them separately, then together as a group. Sometimes an Aunt can help another Aunt to jog her memory on certain events.