I don't believe I will be the one to identify this plant for you but I can certainly help get your hopes up that they are actually something cool before you find out they are just weeds...well now that I see the serrated leaf edges now I'm leaning just more toward some weed, but they do look similair to goji berries which I have just started growing recently, but you would know if they were them because the stem would be woody at some point or at least the whole plant would be a lot more stiff and supported than any weed and goji berry has thicker leaves ok nevermind I think this is definitely some weed... but what you wrote about it being an 8x8 patch and the fact that that patch is then surrounded by a blackberry patch (remember blackberries are spiky) sounds to me like there is a slight chance somebody had a patch of something they wanted to keep hidden or at least inaccessible by others. Now I'm not saying this looks like cannabis to me, in my opinion it does not, not at all, but, we must always remember, there is a form of cannabis (I believe it may be cannabis rudimentialis) that does not grow the same type of buds that are sought after in the medicinal cannabis markets for thc extraction, no they don't produce thc or cbd or anything really in much vast quantities so they are used first and foremost for the production of hemp, which, is starting to become legal again in some states! hemp is better for producing paper and other textiles, and is starting to be regarded as vastly superior, and thereby acceptable, America should be tired from getting all their hemp shipped in from other countries by now anywhow, sorry I'm sure I've confused you enough... my rule I follow is I wait tilll I see flower then i ask everyone if they can identify it by the flower before I decide it's a weed... but sometimes u just know... but u just don't want to believe...

Solidago/Goldenrod I think

ditto....Solidago/Goldenrod

We have the same thing, have you been able to identify this plant?

Can you take photo and start a new thread? This post is nearly 5 years old. I also believe the plant pictured here is a Solidago sp.