Alcohol
You may have noticed that here in PL, it's a bit of a drinking culture; more of a national pastime, really, compared to the country's success at football. Indeed, nothing says 'I've been to Poland' like a suitcase of vodka (a new bride being the second hottest commodity). The Poles have been distilling and draining vodka since the early Middle Ages, and Poland can make a legitimate claim as the spirit's primordial homeland. As such, you should put it at the top of your souvenir list, even if it's not to your taste.
Belvedere and
Chopin are the elite brands you'll find in fancy gift sets, but don't miss
Żubrówka (bison grass vodka),
Krupnik (herbal honey vodka),
Żołądkowa (herbal stomach liqueur) and
Goldwasser with its signature gold flakes.