I work at one of those businesses that buys and sells locally grown flowers. It's ideally suited to permaculture both because so many flowers are perennials and you can stack functions with many food items producing decorative parts.
Echinacea makes wonderful cut flowers and not only does this not inhibit the production of the
medicinal root, harvest the flowers keeps the plant from devoting as much
energy to
seed development. Sun roots are in the same situation. I was even wondering earlier this week if I could increase tuber production on the dahlia's I planted seed for by regularly cutting flowers for the household.
Dill flowers where part of most of the spring bouquets in the store last year. I've also seen colorful kales, ornamental cabbage, and swiss chard. Pretty much any plant in the carrot family produces a very prominent flower.
And branches, bare and otherwise are often used as filler if you're pruning. Shiny bark, colorful bark, gnarly shapes, interesting leaves, colorful leaf buds, berries, pretty much anything can make a random branch work in a flower arrangement. When I started my espalier I gave one peach tree top that had just started blooming to a neighbor and put the other in water and it started to bloom. I actually got a couple of weeks of pretty pink flowers from that.
Think about winding grapevines through arrangements. The leaves can be decorative, the bare vines can be shaped into loops that bind the bouquet together while adding some architectural detail for the eye. I don't think anyone growing grapes doesn't have an excess of vine. Sweet potato vines have lovely heart shaped leaves on the edible varieties and will root rather than wilt in water.
Just pulling likely items for floral arrangements off the top of my head, is producing a list that would work very well for a food forest. Arranging flowers is an
art form, so long as you have a creative eye for design you can almost grow anything at all.
Now there are limitations, except the squash itself, I don't think any part of a squash flower would be durable enough to use. Spinach and most lettuces wouldn't hold up to any handling. Joseph Lofthouse is breeding a
tomato line with ornamental flowers but most tomatoes wouldn't even get an audition.