This box at Atlas Quest has a hint. Try not to read this:
Date: Dec 6, 2007 8:49 PM
I would be very pleased for you to find this box. I went to the library first, but decided I wanted a truly out of sight spot. I chose another location I could walk to. Easily. On the morning of the planting, I was surprised to encounter a man flying an airplane. We didn't speak.
You know baseball. You are perhaps missing your key clue, which hinges on a detail of that sport.
I was worried that my opening lines were too cryptic. See if you still think so after you've logged in.