There are some names with rings in them. The 2 I can think of are Rings of Wonder, and Silver Rings. There might be more. Think there's also a few with elf or elfin in the name.

My friend Bret Clement has an entire series with the name hobbit in the cultivar name:
Arrogant Hobbit
Crafted by Hobbits
Hobbits Gone Awry
Hobbitskin Necktie
Hobbitual Offender
Just Another Hobbit
and my personal favorite, Women Seeking Hobbits

Many of these are plays on some of Curt Hanson's more risque cultivar names, as you can tell!

Linda Michaels also has one called Gotta Hobbit.

There are a few others with the word Hobbit in it. These would be a good start to a theme bed, IMHO.

There's Moldovan's Lord of Rings.

randallpink, you might want to go the AHS database and search on various words relating to the books:

http://www.daylilydatabase.org/

For example, searching on "elves" gives you three possibilities; searching on "elf" quite a few more than that. Use the box "Anywhere in Cultivar name," and, if searching on a word that might be part of another word (e.g. "elf" could be part of "myself," and in fact the first cultivar name found is All by Myself), add a space before/after the search term.

I was curious, and I searched on some names. There is in fact a daylily named Gandalf the Grey, but from what I understand, the hybridizer's plants are hard to find. Might be worth trying to track the plants down though for that name!

Curt Hanson has one named Gollum. Someone has Aragorn. Stoneking-Jones, who registered Gandalf the Grey, has two with Arwen in it. You need to track down this guy!

Morss has A Bauble for Bilbo, as you know. He also has Lilacs for Galadriel, and there are others with "Galadriel" in it. (More Stoneking-Jones!) There's a Saurons Eye.

Oh wow....Stoneking-Jones has a daylily named One Ring to Rule them All. I was doing a Wiki search on LOTR weapons and then an AHS DB search on them. Hit paydirt on my very first search! New idea....

Go to the Hybridizer search option in the AHS database and search under Stoneking-Jones.

There's Rivendell Twilight (Phil & Luella Korth). And more with Rivendell in them.

Cool...! Marc King registered Shadowfax!

Quite a few with "troll" in them. I like Margo Reed's daylilies, 'tho I've not seen her Troll Under the Bridge. Quite a few with "dwarf." Tons of dragon names, tons of wizard names, too.

There's an old one by Frank Childs named Pippin. I wonder whether it's available? He also has one named Merry.

This is pushing it, but there's an oldie named Fellowship.

About other plants...no idea, really, but you might try doing similar searches at other plant society websites, e.g., American Hosta Society, the iris people, etc.