Peah, Chapter 8, Mishnah 5. Most of the gifts to the poor are gathered by the poor themselves out in the field - peah, leket, shichechah, peret, olelos and the like; but maaser ani is distributed and given by the owner himself, since it is a portion he separates from his own produce. The Rambam writes that the owner gives each poor person who comes to him enough to satisfy him, that is, a measure sufficient to meet his need, as it says regarding maaser ani: "V'achlu vish'arecha v'savei'u" - that they should be able to eat within your gates and be satisfied. The question is, what exactly is the measure of "enough to satisfy him," and our mishnah addresses this item by item.
The measures given at the threshing floor:
The mishnah opens: "Ein pochasin la'aniyim bagoren" - we do not give the poor who come to the threshing floor less than the following measures:
"Mechatzi kav chittim" - one does not give a poor person less than half a kav of wheat.
"V'kav se'orim" - double the amount of wheat. Rabbi Meir says: "Chatzi kav" - for barley too the measure is half a kav, exactly as with wheat.
"Kav vachetzi kusmin" - a kav and a half of spelt.
"V'kav gerogaros" - when it comes to dried figs, one gives him a kav.
"O maneh develah" - pressed figs are not given by volume but by weight, and their measure is a maneh, which is the weight of one hundred dinars. Rabbi Akiva says: half of that amount, half a maneh of pressed figs.
"Chatzi log yayin" - how much wine does one give him? Half a log. Rabbi Akiva says that one gives him half of that: a revi'is, a quarter of a log of wine, and that is the measure that satisfies him.
"Revi'is shemen" - according to the first opinion, a quarter of a log of oil. Rabbi Akiva says: an eighth of that.
"Ush'ar kol haperos" - regarding all the fruits not listed above, Abba Shaul said: "Kedei sheyimkerem v'yikach bahem mezon shtei se'udos" - he should be given an amount that he can sell and with the proceeds buy food for two meals.
Between the threshing floor and the city:
All this, the commentators explain, applies when the poor person goes out to the threshing floor, to the area in the field where the grain is threshed, and takes the trouble to make the whole journey - then the owner must give him these measures. But in the city itself, when the poor person comes to his doorstep, the owner may give him as he wishes, even as little as a kezayis. The reason: in the city many people give to him, and he can combine the gifts of many into a large amount; whereas in the field he went specially to this man's field, and therefore it is incumbent upon him to give him enough to satisfy him.