The shard is close to, but not the same as the two sketches found in the book noted below. I think this is a much older shard (Trade Mark)
See books.google.com: A BOOK OF POTTERY MARKS by W. Percival Jervis. 1897; Pg.80. Harker Pottery Co.; East Liverpool, Ohio.
Benjamin Harker, Sr. established Harker Pottery Co. in 1840. After operating for some years he was succeeded by his son, George S. Harker, who carried the company on as G. S. Harker & Co. until his death. His widow and two sons continued under the same style until 1890 when it was incorporated as the Harker Pottery Co.; Rockingham and yellow ware were made until 1879, when the company changed over to white granite.
Noting this information, it seems very likely this shard is dated prior to 1879. This shard is at least 137 years old at minimum, and possible as old as 176 years.