My first instinct since you said it tastes sweet is dill.
It doesn't seem to be fennel because although I don't know if young fennel is sweeter, piney isn't something I think
of with fennel. Edit: I just went in the kitchen and smelled a container we have a dried fennel, and there are some notes in it that could be piney. I don't think I've ever smelled fresh fennel, so there may be a noticeable difference. I also don't see the center section at ground level more typically seen with what fennel pictures I'm familiar with. Also, the branching seems to be consistent to the ground, where fennel has a bit of a stalk. Again, could be too young to tell for that.
I saw another site
looking for an ID on a similar looking plant, and another guess was young asparagus, again, not really sweet I don't think even when young although it definitely can be earthy.
It also could be dog fennel from what I searched, but that doesn't taste sweet when mature.
This site discusses when it's good for kitchen use if in fact it is dog fennel: Herbs from Distant Lands
That's all I have to suggest after doing a brief image match search.