Fort Sheridan Forest Preserve in Highland Park, IL, is a pretty reliable spot for Red-headed Woodpeckers. There were several flying about during my visit back on October 15th. At least two striking crimson-topped adults were caching acorns.
I also noticed a juvenile making sorties from the path in front of me to a certain tree over and over. It was picking up acorns from the path and then using the tree trunk to work on them.
This youngster has some red coming in; look at the lower cheek in the last picture above.
The trees were kind of pretty, too.