This is more of a response to others, admittedly as I don't know if LtCommData is around.

Ok, fixed this response. Yes, there were in fact Atlas F silos in eastern Nebraska. They were associated with Lincoln AFB and the 551st Strategic Missile Squadon.

http://www.members.tripod.com/sms551association/

See my .sig links for the full list

For the record, these silos are hardened underground structures, and thus would have no resemblance to a grain silo.