And now I want to grow... well, not all of the plants in the book, since many of them have limiting factors, for example that they can only be grown in climates more tropical than Maryland (including, alas, the pepino melon, but I have transplants that will be sizable by mid-May, so I'll keep hoping), but more than I'm growing now.
So far I've tried:
Sunchoke or Jerusalem artichoke
Walking Onion, of which I have no picture, and while we're on alliums, my garlic might as well be considered perennial since I never manage to dig it all up so it springs up in every bed it's been planted in. And I've started sea kale this year, and (rather unsuccessfully so far due to interfering squirrels) cow cabbage.
Some other plants I've grown are perennial in warmer climates, for example sweet potato, hyacinth bean, and both Malabar and New Zealand "spinach." In fact, some plants that die here when it gets cold are invasive pests in warm climates; Toensmeier either does not include these or explains carefully and with adequate warnings why he is making an exception. He also makes distinctions between truly invasive plants and those that are aggressive within a garden but don't spread into the wild if you keep after them (running bamboo is an example). I am tempted by Chinese artichoke, a spreading plant grown for its edible tubers, but then I see its Latin name is Stachys affinis (Stachys byzantina, lamb's ear, is a soft, furry bane of ornamental gardens, very difficult to get rid of once you have it, and all Stachys are part of the mint family) and it is described as forming large colonies. So only if I have a place I want smothered in ground cover, I guess.
However, I think I will try wintering over some of the scorzonera we are growing in the demo garden this year (shouldn't speak yet since we only planted seeds Thursday, but I hope it will succeed!). And perhaps find a suitable microclimate to perennialize scarlet runner beans (Toensmeier claims them hardy to zone 7 with lots of mulch). And groundnut would be fun to try, given a large enough trellis (4-8 foot vines).
Here's one more picture, again from a vacation, this time to Belize, where we saw this pepper growing on a small tree. Peppers are perennial, yes! But not in Maryland, sorry.
(Cardoon and pepper photos: Nick Smith; Jerusalem artichoke: Katherine Lambert; the less good ones are mine.)