Try going to the magazine websites. Often they show back issue covers for a year at a time. You might recognize it that way.
Quilter's Newsletter mag does not provide patterns for their cover quilts, so that's one mag you could eliminate. Any idea where you bought the magazine? A lot of places carry only a few different ones, which could narrow down your initial search.
Edit: Hmmmm..... Just followed my own advice and found this one:
http://www.thequiltermag.com/issues/.../holiday.shtml