- Whoever does not leave any bread on his table [to remain there until concluding Bircas Hamazon] will never experience bounty. But one should not bring a whole loaf to the table a the end of a meal just for the sake of it being there. Nevertheless, if no slices of bread remained at the end of the meal, one is permitted to bring a whole loaf to the table. (Shulchan Aruch OC 180 with Mishnah Berura)
2. It is forbidden to destroy pieces of bread that are the size of an olive or larger. As for pieces that are less than the size of an olive, although it is permissible to do away with them, it is nevertheless doing so tends to bring about poverty. Casting them into water is permissible, though there are some authorities who are strict about this if all the crumbs together amount to the size of an olive. (ibid.)
