Kinokoinu

The heartwarming story centers on a Mushroom Pup who is one day born in the yard of picture book author Hotaru Yūyami. It wags its tail just like a dog, but it's unknown if it's a dog or a mushroom. It draws pictures where it shouldn't, and always wants to eat Hotaru's takoyaki.
(Source: Anime News Network)
Note: Includes 8 extra chapters.