This is not a complete list, but thanks to Dan Smith for getting it started! Click on any thumbnail to see more detail on any shirt design.

#12 - Old Forest - 1989 Design by Anthony Hicks. Thanks to Dave M. for the image!
#13 - Ithilien - 1990 Design by Anthony Hicks. Thanks to Dave M. for the image!
#16 - Maggot's Farm - 1993 Design by Anthony Hicks. Thanks to Dave M. for the image!
#21 - Mirkwood - 1998 Design by Anthony Hicks. Thanks to Maeline for the image!
#22 - Misty Mountains - 1999 Design by Anthony Hicks. Thanks to Maeline for the image!
#24 - The Two Towers Design by Maeline Simon.
#25 - Ring Verse #25 - Past Years
#26 - Roads Go Ever On Design by Daniel Smith.
#27 - Feast of Reuniting - 2005 Design by Maeline Simon. Thanks to Jim for the image!
#28 - The Lonely Mountain Front design by Daniel Smith. Back design by Jim Wilkinson.
#29 - 70th Anniversary of The Hobbit Design by Anthony Hicks.
#30 - The Grey Havens Design by Daniel Smith.
#31 - Rivendell Front design by Maeline Simon. Back design by Daniel Smith.
#32 - Mirkwood Design by Daniel Smith.