I guess.... but,
Crops Circles are man made. It have been proven plenty of times to have been made by two English man named Doug Bower and Dave Chorley. Not aliens.
Plus, why would aliens travel billions of miles in space to make shapes in corn field. Its obvious there better things to do than trolling a complet planet only for the heck of it. If there is a intelligent form in the universe, I doubt the would hold themself from making contact with us.