Out near Black Hawk there is a real pumpkin patch - they have had it the last two years and I think it has been a huge hit - my kids love it - Like Ashnat - coming from Denver we missed the "real" pumpkin patches and corn mazes.
We usually also go to the pumpkin area at the Church on the West side (name escapes me now) and play around.
Custer State park has their buffalo round up and fall festival.
We just put up our fall decorations this weekend and now it's 85 degrees - you just cant win!
Edited to add - Saw this in the breakroom here at work this am -
www.fortfear.com -