Looks like an aster. My first guess would be Solidago ptarmicoides, Upland Aster -- check out the link provided and see what you think. You'll have a better shot at a positive ID when it blooms later. S. ptarmicoides is a nice garden plant, by the way, and has recently been reclassified as a goldenrod (Solidago) masquerading as an Aster. Asters and goldenrods keep the taxonomists busy and earning their keep. :) Here is a link that might be useful: Upland Aster

Barberry (berberis). Although not a listed plant on this side of the country, can be considered invasive in some of the Eastern states, you may want to check its status in Pennsylvania

Seagreen, some of the suggestions offered are, while good ones, not necessarily what you are seeking. If it's the actual tree-not a garden mini-that you seek, then you want straight-species eastern hemlock-Tsuga canadensis. And if that is the case-that your main appreciation is for the native tree itself, well then let me tell you that is just as valid a quest as that of the collectors that participate on this board. I really like some of the conifer gardens I've seen. It really is, IMO, one of the pinnacles of skilled horticulture. But that in no way compares-for me-to the wonders of growing, watching grow, cutting down, burning, hehe, let's just say a range of activities, with the woods and tree farm that has been my project since 08. Or of seeing the same processes at work in the relatively less-disturbed areas in my travels. Anyway...the main issue with eastern hemlock these days is an imported (by accident) very destructive insect know as the hemlock woolly adelgid, which is in fact decimating this tree to the east. Michigan has recorded at least a find of tis pest, but I'm not sure of the present status without doing some quick research. But in any case, check that issue out-it sounds like you can still grow hemlock in SE Michigan-but arm yourself with knowledge, should you ever have to treat your plant(s), which is doable, BTW, or if that's just not a go with you. Here in Wisconsin, so far so good. But it has tended to be the case that whatever shows up to our E, it does end up here eventually. Cold winters, blah blah. They said that about gypsy moth-we got gypsy moth. Then two winters ago, when they said it would kill all the emerald ash borers, it didn't kill all of the emerald ash borers. And so on. Would really suck-right around where my land is, it is hemlock that I see coming up as regeneration in many areas. And there is a patch of old growth on the high bans of a lake nearby-this actually has state designation as a legacy stand-so much to lose around there if adelgid comes in. +oM

I agree with jekeesl that it looks like Acalypha virginica, AKA 3-seeded mercury, a weed. You will want to get rid of it before it starts dropping its bizillions of seeds.