The last time we called them, we trapped two kittens in the trap. The mama cat sat next to them for hours and wouldn't move. I opened the cage and released them. She loved her kittens too much for me to take them from her.
If she's feral she'll never be a pet, but if you can trap her you can probably find a shelter that will fix her for cheap. Then you can release her again. Otherwise she'll just get worn out breeding kittens that will either die or grow up to be feral as well. Nature isn't kind to feral cats.