In 1981, Dr. Kevin Vaughn of Massachusetts registered this cultivar, which is named after one of the well known hosta hybridizers of all time, William Lachman of Massachusetts. 

It is a hybrid of "Vaughn Seedling 73-2" × H. 'Frances Williams'.  The clump is large size (18 inches high by 24 inches wide) with heavily streaked foliage and, according to The Hosta Handbook by Mark Zilis (2000), is an important breeding plant. Lavender flowers bloom in July followed by viable seeds.

According to The Hostapedia by Mark Zilis (2009), this cultivar is a sibling to 'Breeder's Choice', 'Mildred Seaver' and 'Christmas Tree'.

The New Encyclopedia of Hostas by Diana Grenfell (2009) states: "Reverts very easily to a marginal variegation or a plain color. Needs dividing once large areas of solid color begin to appear. A wonderful breeding plant but too unstable to be a successful garden plant...An almost imperceptible narrow, irregular margin usually borders the leaf blade."

An article by Warren I. Pollock in The Hosta Journal (2015 Vol. 46 No.1) states that, "In 2010, Dick and Jane Ward. ..registered 'Beautiful Dreamer'. It's a seedling from 'Zany Janie'...with medium green leaves having a pure white margin...mound height about 13 inches and width about 20 inches...Stuart Asch...has a hosta he named 'Beautiful Dreamer' (NR). It's a seedling from 'William Lachman'...Asch's description: "This small beauty has outstanding color and variegation. The leaves have great substance and are nicely corrugated. A wide deep-green edge with a golden cream center is a wonderful contrast."