Id please

This tub was emptied of a dead Heather and planted with sunflowers. The next day this appeared. What is it and how on earth is it this size in a day?

 

Boy, does that look like Ground Elder!

 

Darn, I had better things to do with my garden fork tonight. Least it's to snow tomorrow! Thanks for the id.

 

At least it's in a container. If you see and leaves like that pop up anywhere else, get rid of them and their roots and put them in the bin.