My father puts some silver coins under the threshold of our house and tells me that this is for optimism and a blessing. Is this appropriate? Please, advise.

All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and messenger.

If your father does this as a kind of optimism, then this is not optimism. Optimism is what the Prophet, sallallaahu ‘alayhi wa sallam, illustrated in a narration that there is no contagious disease that occurs without the permission of Allaah or evil omens that prevent a person from carrying out their work. He, sallallaahu ‘alayhi wa sallam, stated that he, sallallaahu ‘alayhi wa sallam, liked optimism which is a good word which a person speaks out. [Al-Bukhari]

Allaah Knows best.