Mr. Ferret

Recently Ive noticed I have a rattle that seems to be coming underneat the car when I start the vehicle, its real quick and its about 3 seconds than it goes away instantly, I can shut it off and restart it and the noise doesn't show up. I wait 10 minutes it does it again. I was told it was the starter replaced that found out it was a waste of time and money, any help would be greatly appreciated, it seems to be coming from directly under the car and its real quick. Tired os spending money guessing problems, getting real expensive lately.