It's just nothing, a physics behind the rice pulling event. A powerful electro magnetic or static electricity can attract the non metallic things, not only rice or flower or something else, it can attract even a stone depends upon the magnetic induction.

Example, the CRT attracts (TV screen) your hair even power off the TV unit. Rubbing of a comb on a wool cloth make a temporary magnetic induction to attract a paper pieces or even rice. Try it and get clear.