put our/your/their heads together
To work together to come up with an idea or solution. If the two of you put your heads together, I'm confident you'll figure out a workable solution. Don't worry, we're putting our heads together to come up with a catchier slogan right now.
put people's heads together
to join together with someone to confer. Let's put our heads together and come up with a solution to this problem. Mary and Ted put their heads together, but failed to provide anything new.