Can anyone tell me what this plant is?

Hmmm it looks strangely like a marijuana plant lol.
But it could be a perennial marigold maybe?

any chance of a joint then?

LOL! Are you serious? LOL! I'm positive it isn't mary jane. Thats crazy : )

Oh yeah, by the way, what is a perennial marigold?

I think you'll have to wait 'til it blooms, then you'll know :) It does look suspiciously like MJ...

Well, I got all paranoid, so I went out and broke off a leaf and smelled it. It smells like a carrot, whatever that means. LOL! I have no idea. Lets just hope the cops don't knock on my door anytime soon...

do you have a bird seed feeder nearby? if yes get rid now :o).
Does it have spines along its stem as its not disimilar to cleome from this photo.

but I do think it is 'weed'. lol

Oh my God! This is insane. I have no idea where it could've come from. Yes, I have bird feeders, my neighbors have bird feeders. I just can't believe this... There were two more smaller ones just like this one, and since I didn't know what they were, I pulled them up and saved this one just to see what it become. I just cannot believe this. LOL!

Yes, it does have spines. Let me go out and take a closer picture of its stems and leaves and I'll post it.

One grew in my garden, curtesy of bird feeder - the policeman who lived next door asked if he could have it when it was fully grown (ie ripe). We had a good laugh about it.
It doesn't actually look like that sort of 'weed' to me. Have a look at google images.

I have shown this picture to a friend who just happens to be in the drug squad and he says rest easy it is from bird seed but the leaf arrangement is wrong for that type of weed. phew.

Ha Ha Silly me!!! Perennial means they just keep coming back every year, What I meant was Bi-annual it grows one year and flowers the next. But it does look like a meadow weed that birds may have dropped, I have yellow poppies in my garden that I have never planted so birds may have left them for me, they look nice but Oh! do they spread, I try to keep them down by dead-heading before the seeds fall.

Oh, thank you, Bob, I wasn't quite sure what you meant. Someone said it could possibley be Queen Anns Lace, whatever that is. I dunno. I just can't wait for it to bloom so I can hopefully put an end to my curiosity with this mystery plant!

queen Anne's lace has small blue clusters of flowers when they flower. i have grown it years ago but cant remember what the leaf is like. i'll google it later for my own curiosity.