I believe what you are looking for may be Valerianella locusta. I found this seed at Fedco and here is the description that comes with it:

3102VC Verte de Cambrai Mâche (45 days) Open-pollinated. A small-seeded small-leaved strain that performs especially well in cool or cold conditions and is the best kind for overwintering. May be the same variety Thomas Jefferson grew in 1810 under the name Candia.

Underneath is a tab that opens a window which reads:

MACHE Valerianella locusta

From Susan Lipari of Alpine, NY: "I grew up in Germany, and mâche was a staple winter salad green. My mother always bought it at the farmerÂs market, wrapped in newspaper. Even here, in upstate NY, Zone 5, it is quite untouched by the cold of winter. I harvest mâche all through the winter, sometimes scraping the snow off the rosettes and blowing on my freezing hands. When the weather begins to warm up in the spring, mâche begins to boltÂIn late SeptemberÂthe seeds germinate and begin to grow. By the middle or end of October I can start to harvest the new crop. I dress mâche with garlic vinaigrette and chunks of orange or tangerine. No ThanksgivingÂdinner would be complete in my family without ÂRapunzel salad." Also known as Corn Salad, LambÂs Lettuce, Field Salad and Fetticus, mâche has a unique nutty flavor.

http://www.fedcoseeds.com/seeds/SeedsOrderItem.php?id=3102&listname=Mache

They also sell: 3114LL Large-Leaf Round Mâche (60 days) Open-pollinated. Vigorous large-leaf type is suitable for sowing in spring for an early summer harvest. Weaver traces this strain back to the 1840s, but for centuries prior to that corn salad was gathered in the wild.

I also found it here:
http://www.horizonherbs.com/product.asp?specific=1492

I just received my order from Fedco so I suppose I could grow a seed now and take a photo for you.

Here is a link that might be useful: How to Grow Mache

Hi Kathy, did you find it? My parents just brought this back from Germany (my dad's favorite). It's called Feldsalat.