Without flowers it will be difficult to tell. For now, I could only speculate that there are few plants like some species of the cold hardy ground orchid ‘Calanthe’& the false green hellebore/Indian poke (Veratrum viride) with large leaves & parallel veins. But flowers are needed for a confirmed ID. For now check out images & information of these two genera. Please give us and update when these blooms. Again, I’m only speculating. Thank you and best wishes!