What is this weed?
We are not entirely sure. Have you seen it flower? Have you tried to pull it and seen the roots?
One suspect is Aegopodium or Bishops weed. A variegated (green and white markings) form is often grown by gardeners as a ground cover, but it is not recommended as it has invasive tendencies. Here is a page about it and how to effectively control it:
The control measures listed would also work for other weeds or unwanted plants.