The first commenter had it right (thank you Correy!). It was a guy selling workplace employment posters. I was mystified at first. The caller left a message asking me to call an 877 number for "federal and state guidelines". Rather cryptic. But the poster scam makes sense in context.
For those who don't know, businesses are required to have several posters up in their workplace to inform workers of their rights. Workers must be paid at least minimum wage, can use workmans comp if they get injured on the job, etc. All of these posters are available free of charge from the government offices that require them. These scammers get the free posters, combine the information into a single poster, then try to sell the posters to business who may not know they can get the posters free.