“In a market primarily attended by non-Jews the likelihood of recovering the money is very low,” replied Rabbi Dayan. “However, where the money was lost in a Jewish school there is a realistic chance of recovering it. Thus, the Tzemach Tzedek might agree that if the owner searched immediately, we cannot disregard it.”
“Similarly, added Rabbi Dayan, “the Rama [259:7] writes that if a river swept away items that have no siman but there are dams that will stop them and the owner immediately chases after them, we need to return them. Rashba implies that the reason is because this shows he did not abandon hope; Tosfos [B.M. 22a s.v. shataf] explains that the fact that only he chased after the items indicates they are his.”
“What did you say about lifnim mishuras hadin?” asked Boruch
“Even after yei’ush one should still return a found item lifnim mishuras hadin,” concluded Rabbi Dayan. “Shulchan Aruch Harav [Hilchos Metzia 18] applies this also to an item that does not have a siman,if it becomes clear who the owner is.” (C.M. 259:5,7; Pischei Teshuvah 259:2)