Please note - at the national level there are lots of resources for creating posters and signs in community and there are things for sale at https://www.signs.com/ccl/.
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