2005 Honda Accord Cpe - Rattles

I have 05 accord coupe v6 3.0 liter and every time I accelerate passing 20 mph I hear a rattling coming out the front of the car also when past 20 mph it stops until I get to 40 miles per hour in I hear the rattling again what could it be? Mechanic said it’s not the heat shield

Why did you not have him try and determine what it was ?