Mishnayos Peah Perek 6 Mishnah 2

לגפה – stone fence set up one on the other without plaster.

ולכלים – utensil of the plough/strigil.

בית שמאי אומרים אינו שכחה – the dispute of the School of Shammai and the School of Hillel regarding the Omer/quantity of grain in a sheaf that he took possession of to bring it to the city and placed it at the side of a stone fence or at the side of the pile and forgot it there.

ובית הלל אומרים שכחה – And it is taught later in our Mishnah (Tractate Peah, Chapter 6, Mishnah 3), that he picked it up to bring into the city and forgot it, the School of Hillel admits to the School of Shammai that it is not forgotten, this is when he did not place it near the stone fence or near the pile. Another explanation: The School of Shammai states that it is nit forgotten, even with Omer that he did not take pick it up, it is not forgotten, for since he had placed it next to a specific place, he would ultimately remember it, and the School of Hillel states that all the while that he did not pick it up, the School of Hillel admits that if he took possession of it and afterwards forgot it, that it is not forgotten, as we will say shortly.