Alicia - I didn't have much luck with Chocolate Cosmos (it isn't a real cosmos - its in a different genus) but boy I love that color. That chocolate scented weed from the prairie states is something like Berlandia or Berlanderia - the best part is the flower disk after the petals fall off. It may even be native to the pine/grass area of this state or of the western edge. It isn't the showiest of plants in the wild but I think there are a few cultivars out there that may have improved flowering.

Chocolate Mint - sorta smells like peppermint patty candy. I have tons of it if you want some. Has dark chocolate colored leaves in the cool part of the year.

There is those chocolate bell peppers - nice brown/red color. Not the best thing for flowerbeds but you might trim them to show off the fruit better.

There are some Dahlias with chocolate colored petals. I don't remember any choco names with them but the color is the same as the chocolate cosmos.

Also look on ebay at Japanese Morning Glories. There are some called chocolate and chocolate silk. They are a chocolate pink color. I grew the chocolate one a few years ago, it was beautiful.

Tammy

there's a 'chocolate cherry' sunflower out there i saw at logan's today. also,'chocolate' morning glories (but mine were inconsistent last year- some were the right color but about half were bright pink or blue instead). oooh- 'chocolate soldier' columbine. i tried choc cosmos at least once and it survived like a week i think. way too much bother. some of the rudbeckias have a large central brown disk-like a chocolate dipped orange. and how about 'cocoa' rose and some of the others ones that are buff or brown? gotta do akebia- chocolate vine. raintree catalog has some new kind of "chocolate" tasting/smelling vine- can't remember the species. if it doesn't have to have chocolate in the name, there's lots of soft brown and maroony-brown plants and flowers that could be used. i got well acquainted, as i was looking for tea colored plants last year for my plot, and it's pretty much the same color range. there's a couple good carexes, pennisetums, a really pretty geranium, the sweet tiny bronze cotula, bronze fennel, nine bark, some of the rex & other begonias for annuals/summer use, 'indian' something iris, several ajugas, and more i can't quite recall off the top. might be fun for contrast and smell to have some "vanilla" accents. like vanilla sunflower would look great with the choc-cherry one. what a great idea for a garden!

There is a eupatorium called "Chocolate" that is one of my favorite eupatoriums. Adele

TJ almost had the name right - Chocolate Daisy - Berlandiera lyrata.

Here are a bunch of CHOCOLATES - I love the idea of this garden Alicia! I just might have to copy you!

Calla - Zantedeschia "Hot Chocolate".
Chocolate Columbine - "Chocolate Soldier" Aquilegia viridiflora.
Chocolate Corn - "Mayes Double Red".
Chocolate Cosmos - Cosmos atrosanguineus
Chocolate Mint - Mentha piperita cv. "Chocolate".
Chocolate Ninebark - Physocarpus opulifolius "Seward" (a.k.a. "Summer Wine")
Chocolate Plant - Pseuderanthemum alatum - Mexican native.
Chocolate Salvia - Salvia africana-lutea.
Chocolate vine - Akebia quinata or five-leaf akebia.
Coleus "Chocolate Mint".
Dahlia "Chocolate Sundae" and "Karma Choc".
Daylilies: "Sweet Hot Chocolate", "Milk Chocolate", "Chocolate Dreams", "Chocolate Splash", "Mama's Hot Chocolate", "Chocolate Fix".
Delphinium elatum "Kissed by Chocolate".
Eupatorium rugosa "Chocolate" .
Foxglove - Digitalis parviflora "Milk Chocolate".
Geranium maculatum "Espresso".
Heuchera "Chocolate Ruffles".
Heucherella "Chocolate Lace".
Nicotiana "Hot Chocolate".
Ornamental grass - Carex comens - "Milk Chocolate" and Carex tenuiculmis "Cappuccino".
Papaver orientale "Royal Chocolate Distinction" (Chocolate Oriental Poppy).
Penstemon whippleanus "Chocolate Drop".
Rodgersia pinnata "Chocolate Wing".
Scented chocolate orchid for indoors - "Sherry Baby".
Tiarella "Mint Chocolate".
Tomato - "Cherry Chocolate", "Cherokee Chocolate".
Viola x williamsii "Velour Frosted Chocolate".

This will be fun!
Nancy the nancedar

Nancy, that is an incredible list. Thanks for your input everyone.

PS There's a bunch of beareded iris with chocolate in the name -- I don't know how many are commercially available anymore, but I found sources for these: Chocolate Swirl, Chocolate Estacy, Chocolate Shake, and Enchanted Mochoa.

There's some daylilies too. I have chocolate splash (really a wonderful burgundy) and chocolate ripple (which is sort of peachy with brown veins).

Here is a site for Chocolate Flower (Berlandiera lyrata).

Here is a link that might be useful: Chocolate flower source

Thank you laurabs. I actually grew a couple of these from seed obtained in a GardenWeb swap and probably lost it after Alberto. Prairie plants do not take kindly to being underwater. It didn't get a chance to bloom so I haven't experienced the fragrance yet. But it is a must-have for a chocolate garden.

What a wonderful list Nancedar provided! With everyone else's suggestions, too, alicia, you should have plenty to get you started.
I've grown the chocolate mint before - it is a must have with a caution. Find yourself a very wide and deep pot. Plant the mint into the pot, then sink the entire pot into the garden. This helps keep the plant from taking over, so long as you watch for any that try to escape over the edge of the pot. Chocolate mint leaves are great to float in your hot chocolate. You can also put a few in with some powdered sugar overnight before using the sugar in a frosting. Adds a nice, subtle, minty flavor. But I digress...
The Eupatorium 'Chocolate' is also a great plant, but needs a lot of moisture or afternoon shade, as it wilts easily on a daily basis. It flowers late, though, so it's useful for extending the bloom season.
For trees/shrubs that could also be incorporated, there's:
Albizia julibrissin 'Summer Chocolate' ($150!)
Hydrangea quercifolia 'Pee Wee'(foliage turns chocolate/burgundy in Fall)
Pittosporum shrubs are said to have chocolate scented flowers
I've included another link I found that includes a plant list for a Chocolate Garden designed over in Europe. You'll have to research some to see if they grow here.
As for my previous idea in another thread for using cocoa hulls to mulch a Chocolate garden, it seems they may or may not (depending on who you listen to) be a bad idea if you have dogs. But let's not clog up this thread with that debate.
Isn't it amazing how many "chocolatey" plants there are out there?

Here is a link that might be useful: The Chocolate Garden

Thanks for the link, transplanted!

What about some native trilliums? Some have a nice deep red flower in the spring and mottled foliage for post-flowering interest.

Here is an example I saw. Trillium cuneatum (Whippoorwill Trillium)

Here is a link that might be useful: Whippoorwill Trillium

Did you know there is an entire nursery dedicated to all things chocolate?? Well, at least all plants chocolate scented or chocolate looking. Check out their website and try not to drool too much-makes the keyboard sticky. The nursery is called Chocolate Flower Farm. http://www.chocolateflowerfarm.com/home

Best of luck.

Here is a link that might be useful: Chocolate Flower Farm

Thee is also a Delphinium called "Bitter Chocolate" but the picture looks a lot like "Kissed by Chocolate" Bitter Chocolate seeds are available through Plants of Distinction in the UK

There is always clematis montana 'Wilsonii' that is purported to have the scent of hot chocolate if grown in a sunny location.