In one of my many circles of information I came across this amazing site for information posters. One was about companion planting which I have seen before but never knew where it originated. Now I have a source. Even though these are based around South Africa there are 15 or so good information posters. Here is the link. http://afristarfoundation.org/educational-resources/
You can purchase or download. There are not based here in the US however.
I asked about buying the 15 poster set and shipping to the US. I will update once I hear back. But the 15% sales tax and $100+ for the set makes it a bit expensive.