I think they're bread pans. They're tapered, have a bottom that would leave a nice impression on the top of the bread and a longer lip on one end to pull them out of the oven with. Google "cast iron bread pan" and you tons of hits. Lodge makes one. Surprised me too as I've never seen an iron bread pan; apparently they're not unusual.
http://www.fleetfarm.com/detail/Lodg...FQiQaQodYQkF-A