Strange sound in Cab?

I'm hearing a sound like a ball rolling forward and backwards inside of a cup upon acceleration or deceleration. I know it sounds crazy but it is what it sounds like. With out prodding anyone, I have 3 confirmed cup or ball in cup rolling around. Help before I rip the dash & center console out!
I have checked any and every possible scenario. Hard to pin down exactly where it is coming from . Under drivers seat, in console, or in the dash. Everyone that takes it for a drive comes back with the same description of the noise. Started awhile ago every now and then. Now it is constant again on accel or decel the ball is rolling inside of a cup.
Not a aggressive sound but it drives me crazy trying to figure out where it is coming from! 2009 Tacoma Ext. Cab

 

did you check all the compartments under the rear seats for something loose

 

ooops I see you have an ext cab not dc sorry

 

yes I have. time and time again.
Hoping that someone else out there w/ a 2009 tacoma knows.
Thanks ! Crazy noise.

 

Did you ever find out op I have the same noise and it's driving me insane! I wanna rip the dash out but not if it's something simple

 

If you aren't the original owner, the PO could have had a kid and a bouncy ball could have ended up down one of the heater vents or god knows what else. Don't really know what to tell ya on that one, crank up the music louder I guess.

I accidentally dropped one of my dog's nametags down in the defroster vent of my old Jeep, it was one of those heavy ones shaped like a circle, and every single corner I went around I could hear it roll across the vent and smack into the wall, then roll back across the other side and do the same thing the next turn.. Never did get it out, just got to the point where I got used to it and no longer heard it.