Iowa Blue Ribbon State Poster Stamps

Can anyone date and identify the source/distributor of these poster stamps?

I acquired a lot of 24 different and it looks like an incomplete set. Twenty-three of them are horizontally oriented, one is vertical. Of the horizontal stamps, I am missing the upper right corner stamp. Possibly a pane of 24 stamps. The lower left vertical stamp suggests another sheet of vertically oriented stamps.

The Blue Ribbon theme suggests a possible connection to the state fair commission.

Anyone have information about this set?

Thanks.

Don