The description of the Garden at Federal Twist on the Garden Conservancy’s website nails it to a tee:

“When we moved into a mid-century house overlooking the woods, I immediately knew only a naturalistic, informal garden would be appropriate to this place. The garden is hidden. You enter through the house, where you first glimpse the landscape, a sunny glade in the woods, through a wall of large windows. Featuring many big perennials and grasses that evoke an “Alice in Wonderland” feeling (many plants are taller than you), the garden is in the tradition of such “new perennial” designers as Piet Oudolf. Visitors have described it as a highly emotional garden. Plantings emphasize structure, shape, and form as much as flower. Begun as an experiment to explore the potential for working in unimproved, heavy clay, the garden is ecologically like a wet prairie, and is maintained by cutting and burning in late winter. Flowers and butterflies peak in mid-July, then a second peak occurs in October when low sunlight strikes fire in the blousy russets and golds of the grasses. A small pond attracts hundreds of frogs, insects and wildlife.”

You feeling it? It is the closest to a Piet Oudolf style garden that I’ve ever seen in person. Lots of ornamental grasses and tall perennials, many with fantastic seedheads.
Oh those phenomenal seedheads: 

And winding paths that just dare you to see what lurks beyond:

Nothing gives me a gardening “a ha” moment more than a well placed focal point and to this day, I haven’t pulled off even one successfully.

It looks so easy when done right: