The White House sources its official tea from the Charleston Tea Plantation, located in Charleston, South Carolina.

The story behind this choice dates back to 1790 when French botanist Andre Michaux first brought tea plants to the United States. However, it wasn't until 1888 that the tea industry began to thrive in South Carolina when Dr. Charles Shepard established the Pinehurst Tea Plantation.

In 2003, the Bigelow Tea Company purchased the plantation and transformed it into the Charleston Tea Plantation, which is now the only working tea plantation in the United States. The plantation spans over 127 acres and produces a variety of teas, including the official tea of the White House.

The official tea served at the White House is the American Classic Tea, which is a black tea blend made from the Camellia sinensis plant grown on the Charleston Tea Plantation. This tea is known for its rich flavor and smooth finish.

References:
Charleston Tea Plantation Official Website
White House Historical Association - Where does the White House get its tea?