Tosefta zu Peah 1:4

How did they give Peah from vegetables? They would not give Peah [from vegetables] except from turnips and leeks, because they are all harvested at the same time (see Peah 1:4). Rabbi Yosei says, even cabbage. Said Rabbi Yosei, it once happened with the son of Nebo that his father gave [the poor] Peah from turnips, and he went and found the poor people at the entrance of his garden [with turnips in their hands]. His son said to them, "You are not concerned with the words of the Sages. Throw down what is in your hands." They threw it down. And he [was someone who] gave double in tithes, and [thus] it was not that he was stingy with poor people, but that he concerned himself with the words of the Sages.