In my Net wanderings, I found this :

http://www.brookes.ac.uk/library/guides/imagesources.doc

(broken link fixed - thanks Rachel!)

It's a library research guide to finding images, and suggests several image-specific search engines.

I had a play with the first one (pic_search) with key words like "tudor rose", "goldwork", "stumpwork" and ...well, there's lots there! Some familiar, some not.

Have fun!