In Parshas Ki Seitzei we learn about the mitzvah of hashovas aveida, returning a lost object. The Gemara in Bava Metzia states that one is not required to return an object which is worth less than a pruta, which is has a miniscule value. The source of this halachah is that less than a pruta is not considered a value, and therefore is not a loss for the person who once owned it. Consequently, one is not required to return it.
Rabbi Aharon Dovid Singer
Rosh Kollel, NMB Kollel
305-972-6508