Yep, Share the Road plates support the Iowa Bicycle Coalition.  I have two plates!!  Wait, I have four plates on two vehicles.  My math skills have gone down hill since we got this no-math-forum.
http://www.iowadot.gov/mvd/ovs/plates/share.htm

RIDE RIGHT and support the IBC.  Be a member.
http://www.iowabicyclecoalition.org/