This is one of those cases where there are two hostas with the same name. One is registered and, therefore, the "official" version of H. 'When I Dream' while the other is a non-registered plant and needs to be renamed to avoid further confusion.

Registered by Hans Hansen of Walters Gardens, Inc. of Michigan in 2020, this giant size (28 inches high by 62 inches wide) cultivar is a seedling of an unnamed streaked sport of H. ‘Empress Wu’ × H. 'Queen of the Seas'. It has blue-green foliage with a creamy white medial (center) variegation.

The broadly ovate leaves are slightly rippled, slightly corrugated and glaucous on top and bottom. Its petioles are white with thin green margins. White flowers bloom from mid-June into July on scapes 27 to 34 inches tall followed by non-viable seeds in white pods.

The registration materials state: "...Large creamy white centered leaves with very wide rippled blue-green margins and chartreuse between the center and margin colors...bluest in spring."

Hosta Helper will call this plant 'When I Dream' (Hansen)
 

There was, at one time, an image of this plant on the Hosta Library and it was credited to Don Rawson of Michigan. Don has contacted us to say that this plant did not meet expectations when it matured so it "...went into the compost pile." None of the plants left Don's garden and so it should be considered extinct.  

Hosta Helper will call this plant 'When I Dream' (Rawson)