HELP!

I know I've shown you this before,

but I really love it.

It's a little weird...

but cool.

Someones discarded art project

 thrown in my back ally.

I didn't have to think twice

before

snatching it up.

Have I told you lately

that I'm a scavenger bird?

Anyway, what I wanted

  to show you

 was this plant

and ask for help.

Every year about this time

 it starts popping up

in my garden. 

 I don't remember planting it,

 but that doesn't mean anything.

Weed or plant?

Help me out.