Help with plant ID

[cdog222]

This guy started growing in my little herb bed last spring. It didn't quite look like any weeds I was familiar with so I let it go for the season. It apparently overwintered just fine, and is thriving. Any ideas? The leaves don't smell of any thing in particular - just smooshed plant leaves

Anyway...I don't really want to dispose of it until I figure out what it is, but it's also taking up valuable real estate...

Thanks in advance!