I got serious about this question and turned to google. I really didn't come up with anything. I found where someone used pallets stacked like the pictures to make a haycock(a mound shaped pile of hay). Doesn't seem like that is happening much today with modern hay equipment. I also found where people used them for climbing plants, that doesn't seem likely out in the middle of an open field. \
My most likely guess is something is brought to the fields on pallets, seed or what ever, then they stake the pallets so they can find them latter.
Well, you explanation is good as any, and far better than some.!
Not to start another silly thread but did you ever drive down the road and see 1 boot or shoe or glove on a fence pole ? Makes me wonder about it. Why just 1 ? Where is the other 1 ? Was it lost in the road and some good meaning farmer picked it up and put it on a pole hoping that the person that lost it might see it and pick it up ? What about the person that lost it ? Are they walking around with just 1 boot on or wearing just 1 glove ? Am I getting to old or just have too much time on my hands to start pondering about such things ?
Waskom John
I'm probably just repeating theories already put forward. Has the subject of aliens been discussed? Maybe has something to do with crop circles?