From the 50s/60s. A family and the neighbor boy take their station wagon to a pumpkin farm. There are lots of pumpkin displays like a scary pumpkin witch and some horses made of pumpkins pulling a wagon. They head home with the back of the station wagon full of pumpkins, and the son and the neighbor boy carve jack-o-lanterns while the mom bakes two pumpkin pies and sends one home with the neighbor. The neighbor boy may or may not have been black.
I found it! It’s Peter Peter Pumpkin Eater by James Reid, published in 1970. I’m so glad I found it!