The Dallas Buyers Club star has teamed up with organisers at Save the Children and Omaze to design the shirt. Jennifer explains she was inspired by her mother's experience in last month's (Jun16) storm, which killed 23 people, revealing she had to pull her car over to the side of the road because she couldn't see."

"She said, 'This rain has been so intense, it just won't stop'," Jennifer tells

Following the storms, the actress joined with organisers at Save the Children to start relief efforts by passing out supplies like "clothes for babies, diapers, toiletries", and she admits she was amazed by what she saw and heard, particularly from the kids affected by the storms.

"There are counsellors who will play with them and they can address any trauma they've been through," she adds. "Kids come in and talk about what they've seen while they are playing, which also gives the parents time and freedom to do what they need to do to figure out their life. It's especially devastating because so many are living paycheck to paycheck and don't have flood insurance."

Each of the T-shirts Garner designed features an outline of a mountain and is emblazoned with the "West Virginia Strong" logo. The 44-year-old explains she wanted the shirt to reflect the state.

"I wanted it to have mountains to show the deep strength of the people in the state," she says. "This is what Save the Children is about. To go to where people are having a really rough time and help."

A proud West Virginian, Jennifer is glad her children with estranged husband Ben Affleck have spent summers in her home state: "Their friends talk about what beautiful vacations they've taken and my kids have too but what they'll almost always say is, 'This summer I went to West Virginia'," she beams, "and that makes me so happy. When you're there, you understand. The pace is more forgiving, the air is beautiful, there are fireflies at night. It's different from what we have in Los Angeles. They are very proud of those roots."