Tosefta for Peah 3:1

מַלְבְּנוֹת הַתְּבוּאָה שֶׁבֵּין הַזֵּיתִים, בֵּית שַׁמַּאי אוֹמְרִים, פֵּאָה מִכָּל אַחַת וְאֶחָת. בֵּית הִלֵּל אוֹמְרִים, מֵאֶחָד עַל הַכֹּל. וּמוֹדִים, שֶׁאִם הָיוּ רָאשֵׁי שׁוּרוֹת מְעֹרָבִין, שֶׁהוּא נוֹתֵן פֵּאָה מֵאֶחָד עַל הַכֹּל:

For rectangular beds of grain that are between olive trees, the school of Shammai says: [Give] <i>Peah</i> [corner of the field that must be given to the poor] from each and every one; the school of Hillel says: [Give] from one for all of them. They concede [however,] that if the heads of the rows are intertwined, one gives <i>Peah</i> from one for all of them.

Tosefta Peah