Note from website editor. At the national level there are lots of resources for creating posters and signs in community and there are things for sale. See links on homepage top right.
It may be fairly simple to create posters affordably from PowerPoint Slides. So the slides in the new deck might be helpful. Find the new deck here. If a poster made in an 11" x 17" size is acceptable - this size can be affordably made and laminated in a do it yourself fashion at FedEx Office.
Agriculture Related Poster
File to the right available for download and document pictured below are the same. This is in 16" x 20" format