Harker Pottery was an American potter in East Liverpool Ohio from the 1840's into the 1900's. At one time they were associated with one of the England Wedgwood potters in the 1870s through 1880s. The only information I could find was from Kowalsky's Encyclopedia of Marks. The turkey pattern is one that was used by other American potters and the same center scene of the tom and hen is copied between the different companies. The only difference between the other potters is shape and flow blue edging. The platter would have had plates with it, usually 12, and there were 4 different turkey scenes on the plates. Wheeling Pottery, Ridgeway, Wedgwood and Doulton also made turkey platters and plates with different turkey scenes. The turkey theme is very popular in flow blue.