Merrill was born on 24 September 1862 in Ripon, Wisconsin. Nothing is known of her parents, but it can be assumed they were financially stable, as private tutors provided Merrill's early education.
Merrill ay ipinanganak sa 24 Setyembre 1862 sa Ripon, Wisconsin. Wala ay kilala ng kanyang mga magulang, ngunit ito ay maaaring assumed sila ay financially pirmi, bilang pribadong tutors na ibinigay ng Merrill maagang edukasyon.