Kristen, there were three different Nakels in Germany -- one in what was until 1918 the Prussian province of Posen, one in what was until
1918 the Prussian province of West Prussia (in German: Westpreussen), and one in what was until 1945 the Prussian province of Silesia
(in German: Schlesien). All three of these eastern German provinces belong to Poland today. Needless to say, before you can proceed, you are going to have to determine which of the three Nakels your great-great-grandparents were from.
You left some vital information out of your query, particularly the names of your great-great-grandparents. Also, you failed to mention where they settled in the U.S. and what their religious denomination was.