Do coins found underneath couch pillows belong to the one who found them?
Thank you in advance!
You can keep the money, and enjoy it, (just remember to give maaser on it). You don’t have to worry that it is in the yeshiva which is owned by the rosh yeshiva, because the dormitory is not a protected place, to say that he acquired it, therefore you can keep it.
CH:M 260-5, Shach 260-18, Hashovas Aveida Khilchoso 11-9 in the name of R’ Eliyashiv zt”l.