The very interesting graves from Uvdal, Norway has a least two pair of mittens, both made of woolen cloth dyed red with madder. One pair is on a young woman, the other on a child. See Vedeler, Marianne; Klær og formspråk i norsk middelalder. Oslo 2007. Unfortunately the author does not describe the pattern.
Another find is from Lodöse, Sweeden. wool, twill weave with stribes. Here you can guess the pattern from the picture of the mitten. I have not not yet found out if it's published somewhere? Åsa Martinsson - http://naama.textilverkstad.se/#post16 - has made a replica of it.
At the Medieval Centre, Jette Mygind made her attempt of a possible pattern and I made a pair of mittens in red wool twill. They work nicely in the cold danish spring weather.
|The original mitten from Lödöse, Sweeden|
|A possible pattern (in white), lower left: the right mitten, lower right: the left mitten inside-out.|