It may very well be Pumpkin! Are you anywhere near Anamosa? This page states that in 1993 Anamosa, Iowa was named the Pumpkin Capitol of Iowa ... maybe seeds from one of the pumpkin patches in the area were dispersed to your garden! http://www.iowaagriculture.gov...
~ I'm an old gal who still loves playing in the dirt!
~ Playing in the dirt is my therapy ... and I'm in therapy a lot!