I checked on a site on how to make eye pillows. It did not give the amount of scented fillers to use but did say not to make it to heavy. It also said not to add to much scent as it can bother some people, just enough for a relaxing effect. It mentioned to use equal parts of flaxseed, lavendar etc.
Here is the name of the site.
www.saveoncrafts.com/arpil.html
Good luck and have fun creating your pillows!!!