What is this?

[lopa]

I am wondering what is this plant that is growing in my raised bed garden. There are two of them in different boxes, almost 8 to 12 inches tall. See attached picture

[PunkRotten]

Looks like something from the brassica family. But it's probably not.

[rainbowgardener]

I don't know, but it would help give people a clue, if you would tell us where in the world you are, so we know whether to be thinking about tropical or cold hardy stuff, etc. You don't think it is anything you planted, they just volunteered?