Hi, I have never seen such cookies in Poland. Let me give you some advice, if you want to impress the polish parent, you just have to prepare bowl of sauerkraut and some vodka. As a snack you should buy a jar of pickled cucumbers. That's it. All right, that was me kidding. I am not funny at all, I am aware of that fact. 

The typical dish of Poland is "soup from fermented rye flour" , which is simply called "żurek" and my favorite one: diamond-shaped potato dumplings ( = "kopytka"). 

In Germany you can buy "Knäckebrot", a swedish speciality:

http://en.wikipedia.org/wiki/Crisp_bread

I don't know if it is popular, but it is found in grocery stores.

Thanks, I'm not sure I trust sending something like this on an 8-10 day trip...but I think I will make it for myself!

If I were in your shoes, I would send them a poppy-seed cake. It's called "makowiec" in polish, and it is a great cake to serve during the Holidays (Christmas). Here are some snapshots:

http://www.rondelek.pl/wp-content/uploads/2008/12/makowiec.JPG

http://pl.wikipedia.org/wiki/Plik:Makowiec.jpg

It's yummy by the way. 

Thanks, but I have to send it in the mail, overseas. I won't be going in person, unfortunately...otherwise I would prepare pierogi, I make them well ;) And apparently you are correct about the wodka :P

Would it be interesting to them to try such a cookie, or is it so uncommon that it would be strange? Dzieki!