I believe I am in a similar growing zone as you over in the West Michigan area. Right now my little homestead is chock full of various edible greens. As a general rule if the plant is an edible then the actively growing part is usually what is best to eat at any give time.
I do harvest and eat the growing tips of goldenrod, wild sweet
pea, queen Ann's lace, mulberry leaves, and wild grape leaves. There are also a couple varieties of chickweed, yarrow, wood sorrel, sheep sorrel, and the flowers of dames rocket.
I've got milkweed still coming up in young tender shoots though I will admit I haven't yet tried harvesting milkweed at this stage though I understand it is edible that way. I usually wait and harvest the buds, flowers, and immature pods. I think normally it would all be up by now but things seem a bit slow this year.
I understand the variety of $^&*@@$
bindweed I have is also edible. There are tons of tender vigorously growing tips of those I
should be trying to find ways to use!