This is an invasive plant known as Epipactis heleborine. Otherwise known as a weedy orchid. Yes, it really is an orchid, and because of that deep, fleshy root system, it is very difficult to eradicate. We have found that a combination of efforts work best since this plant produces tiny seeds as well as spreading underground. Herbicides containing Glyphosate, used at the highest rate on the label can be used on the plants just as they are sending up a bloom. Hand digging is effective if you dig deep enough to get under that root system. Unfortunately, they will easily co-mingle with Woody plant materials and herbaceous perennials. If you miss a few with hand digging or glyphosate, at least pull the stems off before the plant can go to seed. Good luck, as I have been battling this for at least ten years.