It's an Americanised spelling of the Polish surname Chełmiński (for someone from Chełmno, ultimately derived from the word for "helmet"). And also, "Polack" is an ethnic slur.
masculine list:
https://www.behindthename.com/pnl/191050/124079feminine list:
https://www.behindthename.com/pnl/191050/124080