You guys are pretty resourceful... we moved to northern MI a few years ago and we have thousands and thousands of acorns in our yard. What have you found to pick them up easily?
The squirrels are the main cause. WHen the cats are outside the squirrels throw them down from the trees. I'm pretty sure they're trying to hit the cats because they get pretty close and they stop if the cats go inside the house.
The hardware store has some kind of rolling gadget that picks up nuts or spent brass. If I can mount it to my P500 I'll post a full write-up and video.