Tosefta su Pe'ah 4:9

The gleanings and the forgotten sheaves and the peah [taken from the field] of a Gentile are liable in tithes (see Peah 4:9, "unless he declared them ownerless"). When is this? At a time that the Gentile protests [his produce being deemed ownerless, thus rendering it liable for tithes (see Kulp at Peah 4:9)], but if the Gentile does not protest [and consents to his property being deemed ownerless], the ownerless property of a Gentile is [indeed] ownerless, and exempt from tithes.

One who declares his orchard ownerless (see Peah 4:9), the rich people [may] take away the grapefruits and the grapes, [and] the poor people [may] take away the grapefruits and the grapes with defective clusters (olelot). What are defective clusters? Any [cluster] that lacks a "shoulder" or a "pendant." If it has a shoulder but not a pendant, or has a pendant but lacks a shoulder, behold, it belongs to the property owner, and if not, behold, it belongs to the poor people. What is a "shoulder"? Growths joined to each other at the stem, each one next to the other (and see Bartenura to Peah 7:4). What is a "pendant"?Grapes joined to the stem that drop down (and see ibid.).