Many of the lettuces are very ornamental. Rene seeds has some packs of combinations of red lettuces and the spotted fishback letuce..winter greens like spinach and mizuna. Arugala has nice flowers once they bolt and the flowers are eatable.I love the look of the yardlong chinese string beans,snow peas . The Hopi red amaranth is interesting, if you have a goood sunny spot and a good summer green. But queen of all for looks is the Fordhook giant and rhubarb swiss chard. What presence. Kohlrabi is interesting.

You should consider adding some of the interesting Kale varieties. They are highly nutritious, very hardy, and easy to grow. The Lacinato has dark green upright savoyed leaves that add great color contrast, and the "Peacock" strains add splashes of white and pink that are as dramatic on a plate as in the garden. Carrots can test the skills of some gardeners, and are a good indicator of the health of your soil, the frilly leaves are a nice contrast to something bold. Lettuces come in many colors and leaf forms, Bulls' Blood Beets add deep maroon accents. Tall heirloom corn varieties can bring some height contrast and interest in the fall.

If you have something for them to climb on, runner beans come with scarlet flowers or a few other colors. If you can find any, the Blue Shackamaxon pole beans have been grown for ornament for a long time, and produce nice black beans (good for sprouting also). Some people like the look of eggplants in their flower beds.

Carrots can be particularly useful if you grow spring bulbs like tulips. Plant them several inches away from the spring bulbs. As the tulip leaves die back more and more, the carrot tops grow to hide them from view.

I planted Purple Royalty and Yellow Wax bush beans throughout my flower borders last summer. They made nice compact plants (maybe 1.5x1.5 feet at most) and the leaves of the purple beans had nice plum-colored veins. My theory is that they added nitrogen to the soil while also providing me with beans. Not sure if my theory holds water, but everywhere I planted them I had gorgeous flowers too.

Peppers (unless they're tall plants that desire caging/staking) and herbs are easy to relocate out of your garden area and into alternate/mixed beds. That can clear up a good amount of space. Short-growing pepper varieties with natural leaf variegation (such as the hot "fish pepper") look great on display in a flower garden even before the flowering/fruiting.

I would definately add eggplants. I have not liked them my whole life but last year I grew some to expand my summer garden. We grew 4 varieties. Our absolute favorite was a small white and purple striped one which at the nursery was just labeled striped. As best I can tell it is called Listada De Gandia Eggplant which is available at Baker Creek Seeds. We loved it, the flavor was great with alittle nuttiness. We cooked it chopped with onions and peppers to go with eggs every morning.

We also grew Ichiban a standard black/purple eggplant. It was way better than store eggplant probably just due to being picked earlier and being eaten fresher.

We grew Hansel and Gretel (hansel is dark purple and gretel is white) gretel tasted ok but wasn't prolific enough to bother and wasn't as tasty as Listada De Gandia Eggplant. Hansel was ok but Ichiban was more prolific.

The Listada De Gandia Eggplant is not as big or prolific as the regular eggplants but it has earned a spot in my garden.

We would also make moussaka with the eggplant. My whole family likes Moussaka.

I'm one of those people who may admire veges' beauty more than any other plant's so I'm a bit biased...
I don't know the science, but I think that pretty much any old-fashioned veg, well-grown in healthy soil will be vitamin/nutrient dense. (Modern culivars often have a lot of nutrition bred out of them apparently.
Note, these are all cool-season plants:
I like bitter, so I vote for radicchio. Lettuces:'drunken woman', royal oakleaf and 'marveille de quatre saisons' are very handsome.
Giant red mustard, rocket. Salsify has cool purple daisy flowers

Lettuce is just not high in vitamins or minerals. It does have compounds that make it a borderline medicinal plant, detoxifying liver and blood, which is great after a winter of stews, wine, pasta, and other heavy things. Most salad greens from the brassica family have a lot more (arugula, tatsoi, mustard greens). But lettuce is much better when home grown.

Carrots are not much better home grown. If your seller left them in the field past a few light frosts, local carrots are every bit as good as those you grow.

For show, productivity, and being better home grown, chard is tops. Pole beans or tomatoes produce a lot, too, but they will not fit in the flower beds.

If mixing your vegetables in with other plants be sure you're not using a poisonous slug bait. I heard a garden talk once about a gal who was poisoned when eating her strawberries because of the slug bait she'd spread.

For the vitamins - spinach & herbs. My kids did some research for a 4-H project on herbs & I was surprised how many minerals & vitamins they had. A little bit goes a long way with greens, so don't over do it. Thyme is a nice edger. Oregano a nice mounding filler. Herb blooms are lovely, but then the herbs aren't as tasty, so keep 1/2 of the plant clipped. Lemon balm is tasty in small amounts, but can be an invasive reseeding plant if you don't keep it clipped.

Your summer salad greens can go in the shade of your other plants & in patterns alternating red & green. If you start from seeds you'll have dozens of plants to tuck here & there.

Even flowers can be eaten in salads...

Here is a link that might be useful: edible flowers for salads

Nasturtiums. Beautiful and tasty in a salad. Flowers leaves and seeds.

Agree with peppers, as some are quite ornamental, including ones that are also good to eat. Purple varieties and Thai varieties can add a lot of color. In zone 5 you'll need a spot with warm soil, or sneak a black pot in there somewhere.

Lots of good suggestions here, I only have a couple to add. If you have a trellis, then spring peas. They can have pretty flowers, I especially liked my Dwarf Gray Sugar peas last year for their purple tinted blooms, and fresh peas have the best taste. Then for summer, I was thinking a red okra, because the plants themselves have striking red stems and pretty yellow hibiscus-type blossoms.. But I don't know how difficult it might be for you to grow okra since it needs a fair amount of hot weather. Hmmm, what about thai basil? It has purple stems and contrasting green leaves. Cheers!

Hi Strouper2... Although all varieties of lettuce are low in calories those with darker leaves have more nutritional value. So for example plant Romaine in preference to Iceberg lettuce. You can get a full lowdown on planting lettuce and the health benefits at the link below.

I'd try tomatoes to add a splash of red fruit amongst your plants, maybe mixed with squash for their contrasting big yellow flowers.

Hope that helps. John

Here is a link that might be useful: Allotment Heaven: Lettuce

Thanks for the hyperlink, I will start making better use of my egg shells now. So far they have just been added to my "compost" I add to my garden each day.

When okra blooms it looks like hibiscus. Huge white flowers with deep purple centers. They grow to be 10 -15 feet tall and make a great backdrop for other plants. The okra is fantastic grilled too.

Wow everyone thanks for all the great info. My beautiful wife tends to be the more picky one so I usually have to think of her taste when I'm making something (she's all meat and tatters except for her salads & the smoothies that I make her). I was thinking about trying out some different greens like mustard, some cabbages and the okra sounds like a really good idea. Last year I got really hooked on basil & I blended with it constantly. I also grew a plant called Amaranth because I had the seeds. I did a little research and they say that they eat the leaves in Asia all the time & that they're better for you than spinach so I'll probably do some more research on that too. Thanks again for all the great ideas I love hearing them.

The Japanese mustards are delicious and sometimes beautiful, especially in the fall with the red ones. They can be quite mild, or hot like wasabi, depending on the variety and how you grow them. amaranth is a good choice if you want something a little taller.