put (something) in (one's) head
To cause or prompt one to think of something; to plant an idea or thought in one's head. Why did you go and put the idea of joining the military in his head? Chris put it in my head to apply for social welfare payments while I get my business up and running. Who put that ridiculous notion in your head?
put something in(to) someone's head
Fig. to give ideas to someone who might not have thought of them without help. Who put that idea into your head? No one put it in my head. I thought of it all by myself.