Plant ID: Mystery Mint Family with no Mintyness

This plant has popped up in several places on my property. It has square stems, so mint family (Lamiaceae), but has no mint smell or flavor (yes, I chewed a bit of leaf - don't do this at home, kids!). Anyone know what it is?

It looks like http://en.wikipedia.org/wiki/Lamium_orvala or some other plant from the Lamium family. I like to rip out the flowers and suck the sweet nectar at there base.

It's one of those maddening "I know it, but..." things
It looks like they're pretty tall plants?
Off topic, but while looking at Lamium images,
I finally got round to finding out that one of my friendly garden 'weeds' is Lamium purpureum
thank you-I've been meaning to look it up for years!