Farmer Giles is the one about the farmer who becomes an accidental hero when he first hits a giant in the nose with a blunderbuss shot, then somehow manages to hit a dragon's wing with a magical sword.

Nope - not remembering giants. I know I've read it. I've read everything Tolkien multiple times. Have you read Roverandom?

I've never even heard of it. The only other JRRT book I've read is the Silmarillion.

Roverandom is about a toy dog that goes on an adventure - the moon is involved. It's a kiddies book. It was originally written for one of Tolkien's little kids that left his toy dog on the beach.

It sounds adorable!