To tag on to this discussion, the cross stitch stitch is VERY period.
But modern subjects and styles using that stitch aren't.
I was told that one of the first samples of "Polish embroidery" I did
in the SCA was an example of folk embroidery and not period. I didn't
know any better and didn't have much to base my embroidery on but a
blip from the internet. So the bodice was packed away.
Since then I have documented this style of "Kashubian" (an area in
northern Poland) to late period on an altar cloth and woman's veil.
The sites Sofya listed are excellent sites for samples. I have found
with my Polish research that although I may not have documentation
right now, that doesn't mean it won't surface later.
Remember, never say never...