The gas pump did not shut off and I overfilled the tank with it spilling out. I now have a gas smell in the car. Similarly, One time I spilled gas around the filler neck while adding gas from a Gerry can, same thing I had a gas smell in the car for about two weeks, very strong in the trunk. Did the overfill leak into the trunk, seems so to me

thanks

It may be time for a new fuel sending unit. Pull back the carpet in the trunk and remove the little access panel held in place by 2 screws to examine it for corrosion.

Two things may have happened. First, the drain tube from the filler neck rubber 'funnel' goes inside the trunk and down to the ground. I have seen this tube weathered or the nozzle on the rubber 'funnel' cracked. Then the gas drips down inside the trunk.
Second, an overfill may have flowed out the seal on the top of the tank connection. There is an o-ring to seal the tank opening on top of the tank. It may have weathered and cracked. When over filled, it leaked on to the top of the tank.
The good news is both will air out with time. Check the trunk for the tube/funnel problem and repair if needed. Leave the trunk open to let air circulate and the smell to go away.