It's one of the Lamium genus, most likely Lamium galeobdolon, (common name Yellow Archangel) assuming it grows to a few inches tall and doesn't just get to a couple of inches. Lamiums do well in shadier areas - there are other varieties for groundcover with white or pink/purple flowers, such as L. 'White Nancy' and L. 'Beacon Silver'.

I' also go for yellow Archangel. I have it under my beech tree and it is just coming into flower. After that I usually pull most of it out for other plants to flourish. with the flowers it gets to be about 10" tall.

Thankyou very much.

As Klahanie says, it can be invasive. But there is a form called 'Hermann's Pride' which is well behaved, only forming a small clump