Digitalised medieval manuscripts are a wonderful thing - though, I have learned, they can also be a wonderful time sink. However, when you are looking for image sources for medieval stuff, those illuminated texts can be a treasure trove. Calendar illuminations are one thing I have found especially helpful in quite a lot of cases, as they show working people doing agricultural jobs - dressed in simple, suitable clothing for the most parts.

One very nice digitised manuscript is the Bamberger Psalter, dating to 1220-1230. It has a lot of text (of course!) but includes both a calendar and some splendid full-page illuminations, one of them showing a knight in shining (well, more or less) armour (fol 63r, looks like David vs. Goliath to me).

You can have a look at the Psalter on the webpage of the Bamberger Staatsbibliothek. Have fun!