Glurb is a troll who guards the bridge below your embassy. He is VERY hungry! He will ask for random things each time you feed him. For my particular game, I must feed him 9 apple oatmeal (7 oat, 4 apple, 15 min) from the Trail Kitchen and 17 milk from the cow pasture. Feed him within the 8 hour time period since you met Glurb to receive 5 emerald and 250xp.
Also if you do this you have completed the first part of the quest Feed the Troll and will receive 540xp!