Hearing a rattle When I start my Car?

I have a 1995 Toyota Camry 130,000 miles, well maintained. A few days ago I was parked on an incline with the e-brake up. When I went to move it yesterday I took the e-brake off put one foot on the brake and one over the gas since there was a pole in front of me which I did not want to hit. Immediately after taking my foot off the brake to back up I hit the gas (but not hard just enough so I'd back up) so I wouldn't go into the pole, the car made a rattling noise but drove fine. Today when I went to start it there was a rattling sound seeming to be coming from underneath the car on the drivers side. I went under checked all the fastenings on everything, checked the tires everything was tight, checked and tightened anything with a screw on the penger side of the underbelly and the rattle is still there. Any mechanics out there with an idea of what it could be? The car does not rattle while I'm in motion, it just makes the sound when its starting up. Thanks