something in the mullein family?

It's a white form of Verbascum - probably Verbascum chaixii 'Album', but there are other possibilities. Isn't it lovely!

I grew Verbascum "Flush of White" for the first time this year, but its leaves are rougher and more of a rosette on the ground.

I've just googled that one and found a mullein/verbascum with purplish centre rather than orangey/yellow as this photo shows. How about the verbascum called Gainsborough?

Gainsborough is yellow, so it's not that. Anyway - we agree, some sort of verbascum.

Erm yes ok, some sort of (muttering, cough) verbasc - um, MULLEIN. lol
This is pale yellow tho isn't it?

Youngalistair will have to clarify - in the photo it looks white with yellow stamens in the centre to me.