They're actually my mom's eyes. Her dad's maternal grandma was Portuguese or perhaps even Sephardic.
Strong South European genes, if I may say so. There are a few Polish-Greek families in my home city and you could easily pass as their cousin, but in fact Portugal was the first thing that came to my mind - my former university had a few exchange students from there and you definitely have something similar about your appearance (at first glance).
Just reminding everyone that e.g. southern Poland has a relative majority of dark-haired people, a lot of them with dark eyes too (ethnic Górale Podhalańscy for example).
In general, the most common hair color is something girls call "mysi" ("mousy"?) unhappily - it's something between dark blonde and light brown with a greyish twist. A lot of women hate it and dye them lighter, as Magdalena wrote (one can always guess by the slightly darker color of their eyebrows). Poland being a "blonde" country is a myth, although you'd meet quite a lot of light-haired people around.