The shovel plow drawing and text above is from page 49 of the May 1843 issue of "The American Agriculturist".
The hand-forged shovel plow iron shown in the photographs below was found in 2008 on the Southampton Township, Somerset County farm that formerly belonged to Alonzo Lepley, and a line of Lepleys before him. The farm is presently owned by one of Allen Korns' grandsons. This shovel plow iron was blacksmith-made, and it was probably made right there on the farm, since some of the Lepleys were blacksmiths. In use, the convex side of the iron faced forward. The tang at the top of the iron was probably used to help to secure the iron to the wooden plow frame.
According to my cousin (who found this iron), the shovel plows that were still around when we were children had metal frames. The tang, and hand-forged construction of this shovel plow iron indicate that it was from a wooden-framed plow.
My cousin recalls that when we were children, this simple type of plow was sometimes used for opening up furrows for planting potatoes. From what I have quickly read since receiving these photos, in the early days of our country, shovel plows were the primary tool for breaking up the ground.