ager, rage, gear, berg, dreg, gree, eger, germ, ergo, ogre, gore, goer, regs, ergs, grue, urge, grew, grey, gyre.
Your query has returned 4 words, which include anagrams of reg as well as other shorter words that can be made using the letters included in reg.
The words in this list can be used in games such as Scrabble, Words with Friends, Wordscapes and other similar games.