The first time he found one was the morning after the full moon. He was getting dressed and it was laying on the bottom of his bag. He took it out and look at it before deciding to ask Mitchell about it when he showed up. Mitchell ended up being almost an hour late and by the point he was so annoyed he'd forgotten about the dog biscuit.
After that he found them in random places throughout the day. In his sock drawer, on top of his glasses in the morning, and on one occasion shoved into the toe of his shoe. Annie and Mitchell were never around when he found them though and by the time he saw them he'd forgotten about it again. After close to two days he was just embarrassed to bring it up. So instead he slowly gathered a collection of dog biscuits in a tin he kept on his dresser.
It was two weeks later when they stopped showing up. At first he thought they'd just gotten better at hiding them, but when three days had gone by without finding one it was clear no more were coming. For the next week he kept an eye open for them anyways, but figured whatever had driven Mitchell and Annie to leave him dog biscuits had run it's course. Still it left him feeling a bit disappointed to go through a day without finding one.
After the next full moon he trudged up the stairs to his room. The previous night had been more draining then usual and he just wanted to sleep. With a sigh he flopped down onto his bed. The sigh quickly turned to a grunt of annoyance as something dug into his thigh. He pulled the offending object out from under his leg and looked at it. Sitting in his had was a dog biscuit.
With a grin he got out of bed and walked to the dresser. It wasn't until he heard the clank as the biscuit hit the bottom of the tin that he actually looked into it. It was empty except for the biscuit he had just dropped. With a smile he closed the tin and fell back onto his bed laughing.