I have a medium sized container where i have planted three or four different kind of seeds...but i don't think this is one of them. I'm pretty sure it came up and grew nicely of its own accord.
There are some "weeds" that i consider desirable but i don't think this is going to be one of them.
An ID would really be appreciated. The flowers you see fully opened are 2cm (.79 of an inch) wide) and have delicate petals. Any ideas?