Me’amer refers to gathering harvested grain into sheaves or piles. Similarly, one who gathers picked fruit and places them in boxes or piles transgresses Me’amer, as does one who gathers cut branches or reeds to use as fuel.
This melakha, as a rule, relates to objects that grow in the ground and are still located in the area where they grew. This is because the harvest is generally gathered where it grows. However, some types of produce are gathered in two stages. For such produce, both stages are prohibited by Torah law, even if the second stage does not take place in the field. This is the case, for example, when producing a pressed fig cake. The first stage in this process involves gathering figs from the field, which is prohibited on Shabbat on account of Me’amer. The second stage involves pressing them together to produce a cake. Doing this even at home is prohibited by Torah law as a tolada of Me’amer, since this is the standard way to form these cakes (SA 340:10; MB ad loc. 38; see Menuĥat Ahava 2:5:2).
Gathering fruit scattered in a yard is not prohibited by Torah law, because they are not located where they grew, yet the Sages nevertheless prohibited gathering them because it resembles a weekday activity. However, one may collect a few pieces of fruit and eat them. If the fruit fell in one place and did not scatter very much, one may collect them and put them in a basket. If they fell into gravel or dirt, even if they are all in one place, one may not gather them and place them in a basket, because doing so resembles Borer. However, one may pick them up one at a time and eat them (SA 335:5).
One may collect fruit that is scattered inside one’s home, because gathering items inside does not resemble Me’amer (MB 340:37).
Although according to Torah law, Me’amer applies only to things that grow in the ground, the Sages forbade collecting salt from salt mines. Since this salt looks like it grows from the ground, collecting it resembles Me’amer (SA 340:9). Based on this, several Aĥaronim rule that one may not gather eggs that were laid before Shabbat (Ketzot Ha-shulĥan; however, Shevet Ha-Levi 4:39 is lenient). Eggs that were laid on Shabbat are muktzeh, and therefore one may not pick up even one egg.
Me’amer does not apply to items that have undergone major transformations. Thus, one may gather cooked fruits together. Similarly, gathering clothing made from natural fibers is not a problem, since they have been transformed from their original state (AHS 340:3).