There were so many, we dug them all out but I stuck one in a pot to see if it would grow so we could identify it. Apparently, it will not so this photo is of the dying plant! So, the stalk of the plant isn't red, but green with red fuzz. The stalks of the young leaves are red though. I had a look over the neighbours fence and don't see anything similar but there is a thriving climber so it might be hidden. Thank you for your help.

It's a treeseedling, and I'm pretty sure it's some chestnut, some species of Aesculus. If there is a mature tree around, it's probably been hidden by some squirrel. Unless you have a really big place, I would weed it or dig up and pot if you want to watch it for a while.

dont know if you have a plan ... but see all those sprouts down on the bare branches... most likely.. this thing could be rejuvenated ... one thing for sure.. it could be thinned out and probably enjoy that also ... i would start with any branches that cross each other.. and are rubbing on each other ... unless someone here told me no .. lol ... ken

Could you possibly get another picture of the plant from the side,so we can see what it looks like from the ground up? Looks like something in Solanaceae.