Related sobre Peah 1:13

These are the things that have no set amount: the peah, the bikkurim, the r'iyah, charity, and learning Torah. Peah has a minimum amount but does not have a maximum amount. [If] one makes his entire field peah, it is not peah.

[If] he did not give [Peah] from the standing grain, he gives from the sheaves. [If] he did not give from the sheaves, he gives from the pile of grain. [If] he did not give from the stack of grain, he gives from the heap (=כרי, see B.M. 9:5), until he [makes it into a] stack (see Peah 1:6), and if he [makes it into a] stack, he tithes it [first] and then gives it [to the poor]

[With respect to] vegetables, even though they are gathered as one, they are not brought in for storage [and therefore are not liable in Peah, see Peah 1:4]. [With respect to] figs, even though they are brought in for storage, they are not gathered as one [and therefore are also not liable in Peah].

He who takes out the green onions for sale and leaves the others to ripen for storage (=המארג, see Jastrow) is liable at the beginning [of his harvest] and is liable at the end [of his harvest]. [If] he had four or five grapevines, and he harvests them and brings them [for storage] inside his house, he is exempt from Peret (Peah 7:3), from the forgotten sheaf, and from Peah, but he is liable in Olelet (Peah 7:4). And if [any vines] remain [to be harvested], he gives from the remainder [only] on behalf of that remainder itself [but not on what he previously brought inside his house]. One who thins out [his produce, see Peah 3:3], gives from what remains [on behalf of] that remainder itself [but not on the thinned-out portion]. Said Rabbi Yehudah, in what context does this apply? With regards to one who thins out produce in the marketplace, but one who thins out produce inside his house, he gives from the remainder on behalf of everything [including the thinned-out portion].

They cannot take the [gifts] of a Kohen [given as a favor] from [that] Kohen, nor [the gifts] of a Levi from a Levi.

A Kohen who sold a field to a Yisrael on the condition that the tithes are his forever, and he dies, the tithes do not go to his sons [following the GR"A]. [If] on the condition that the tithes go to his sons and he dies, the tithes [do indeed] go to this sons. [If] on the condition that the "tithes are mine the entire time the field is yours (i.e., belonging to the Yisrael), and [the Yisrael] sells it to another, even though [the Yisrael then] came back and bought it [back from the other person], [the Kohen] does not receive any tithes [after the initial sale].