I came across and interesting article on the Metropolitan Museum's Web page that states the will have an "Open Access Policy" to images they believe are in the public domain. So I put in 'Medieval Textiles' and an 'good' image of Courtiers in a Rose Garden: A Lady and Two Gentlemen came up with the Public Domain symbol displayed.
Then I put in 'Medieval Embroideries' and got very excited. (This is a section of a larger work.)
I am going to be able to look at and uses as inspiration such a range of work.