Good morning, In areas with a good food supply (such as near a forest preserve), it is not uncommon for coyotes to live in small family groups or packs. A pair raises one litter per year, with an average of 5-7 pups born each year. While most of the young typically disperse by late fall to find their own territories, some of the young will remain with the adults to help raise the next year's litter. Seeing a group of coyotes together should not be cause for concern unless they are acting aggressively towards people or pets.
Depending on the height of the eyes, it is quite possible that the other eyes that your friend saw as he looked back may have been deer watching the coyotes.
You can find more information about coyote's life history and how to live with coyotes at: http://web.extension.uiuc.edu/wildlife/directory_show.cfm?species=coyote This page also provides access to a very good report on an urban coyote management study that was conducted in Cook County, IL: http://ohioline.osu.edu/b929/pdf/b929.pdf
If you have further questions, please feel free to contact me.