Phil Stevens wrote:That looks a lot like St John's wort. If it spreads like crazy and gets heaps of yellow flowers in the summer, then that will be your clue.
Alot of Saint Johns wort species have tiny black dots on the leaves. At least some of these dots in some species are actually clear so if you hold the leaf up to the light you can see little pin pricks of light. That might help now vs waiting to bloom.
If it turned out instead say to be some kind of small spurge it would bleed white when you tore a leaf or stem.
If it is some kind of herb that can be used in tea, crushing the leaves and giving a good sniff might give a clue in terms of aroma.