Handle the plant and crush a leaf in your hands and smear the juice all over your hands. Take a leak and wait to see if it kicks in. Any swelling means you gots yourself Horny Goatweed!
Nice try but I don't think so. Here are 2 pictures; one of the plant and one of goatweed. Notice the difference in the leaf and also in the flower. On the bush, the flowers grow in a clump rather than spread out.
Would it be elderberry? Our red elderberry has white flowers in clumps like that with similar leaves. they don't start with the purple colour though.
If this drives you crazy, the USDA has an identification flow chart. The dents on the edges of some of the leaves caught my eye. Could be some kind of damage, or could be a slit developing.... Either way be careful incase its giant hogweed.
Milkweed can be 15' tall and take on a bush-like appearance as it throws babies from roots - and they can be perennial. Those flowers are pretty milkweed-ish too; purple turning to white. But, probably something else since the leaves are saw-toothed.
Wild. We've had more than this one bush but never have known what it is. Decided to post and see if someone could help.
I made the mistake of planting cat mint for our cat years ago in an outside pot on the deck. A decade later I was visiting with an elderly neighbor, we went down his canyon to see his beehives and artificial stream/pond. I asked him what the plant was growing down there in the canyon and he said "wild mint". I was so embarrassed I did not let him know that was my cat mint from years before. He gave me some honey that fall and wrote "wild mint honey" on the lid I still feel bad about that, but also glad for his enjoyment from it God rest his soul. Anyway, it is very possible that could be a similar situation from one or your neighbors and carried by bird or wind Backwoods Savage .