If by “rain of money trick using rice” you mean a ritual where rice is used to attract or make money “rain,” there are several folk/spiritual versions of this idea.
One documented example uses rice symbolically: rice is thrown in different directions as a representation of sowing blessings, and rice thrown upward represents a symbolic “rain” of blessings.
However, there is no scientifically proven rice trick that causes real money to appear or multiplies money. Claims that a ritual can literally create cash are often superstition or scams. Recent cases in India involved people being promised a supernatural “rain of money” or money multiplication and being cheated.
If you mean a specific viral rice + money trick (for example, rice in a bowl/glass, coins or currency, salt, turmeric, etc.), tell me what ingredients or steps you saw, and I can explain exactly how that version is supposed to work and whether there is any real basis behind it.