[According to the New Post-Office Laws]The Illustrated London News, vol. 40, no. 1140, p. 401.
April 19, 1862
According to the new post-office laws in the United States money can be sent through the post in the shape of money orders, at the rate of 2½d. for every ten dollars, and seeds, cuttings, and roots can be sent through the post at the rate of one halfpenny per ounce weight.