Errant plant

[Grannygardener]

My daughter has this plant growing in her garden and it's not one that she has planted. However she rather likes it and wants to know what it is and is it invasive. Can anyone help, please?

Click for a larger image.

[bluebird]

Your "I didn't plant this" plant is Bladder Campion (Silene vulgaris) commonly found growing in the wild especially roadside and in recently abandoned areas. We used to have fun as kids popping the balloons. Okay, I admit I still do that when I find one.
It will readily self seed so one might not want to have it in their garden.

You can read more about it at my pal, Walter Muma's wildflower website.
http://ontariowildflowers.com/main/species.php?id=352

[Grannygardener]

Thank you Bluebird for the reply. Don't think she'll want to coddle it then. She's pulled enough tenacious weeds out of my flower beds in recent years to not want them in hers. Edie