Is it permissible to pick ears of grain from an abandoned field after searching for its owner without success, and what are the legal implications of that?

It is permissible to eat from the fruits of the aforementioned field, based on the Prophet's (peace and blessings be upon him) saying: "Whoever partakes with his mouth of a necessity, without taking a provision, there is no blame upon him. But whoever takes anything out of it, upon him is a fine of twice its value and punishment. And whoever steals anything from it after it has been stored in the threshing floor, and its value reaches that of a shield, then cutting off [the hand] is due upon him."