Bava Batra, Chapter Four, Mishnah Eight
Mishnah eight discusses what is sold as part of a field.
1) If a man sold a field he has also sold the stones that are necessary to it, and the canes in a vineyard that are necessary to it, and its unreaped crop, and a partition of reed which covers less than a quarter-kavs space of ground, and the watchmans hut if it was fastened down with mortar, and ungrafted carob trees and young sycamores.
This mishnah lists the things that are sold with a field. Tomorrow, in mishnah nine we will learn a long list of things that are not sold with a field. The list of things that are sold with a field includes things that are a necessary part of the maintenance of the field such as the stones used for fences and the canes used in a vineyard to grow the vines. It also includes the produce still attached to the ground and similarly the watchmans hut if it was attached to the ground. [Note: there are other versions of this line concerning the watchmans hut]. It also includes some small, as of yet insignificant trees as well as an insignificant portion of a reed partition. Since these things are not significant in and of themselves they become included as part of the field.