My little shih tzu puppy, Gracie, has a very bad habit of chewing on leaves, grass blades, and sticks when she’s outside. Instead of going to potty right away once I take her outside, Gracie has to run around, sniff around in the grass, and chew and eat anything that comes in her way.
Sometimes, she drags her “toy” to the top step near the front door and chews on it. See below…
I do try to take leaves and sticks away when I can. But I’m guessing the leaves are pretty harmless. I don’t think my baby gets the concept of fetch because whenever I throw a ball, she just stares at me and tilts her head funny as if saying “What, mama?”

She's probably teething. Dogs just love to chase blowing leaves. I sit an adult shih-tzu and he STILL loves to chase leaves. Sometimes, he doesn't watch where he's going and runs into lawn furniture. He's a silly thing.
I think she is teething. I can't wait to see how she reacts once she gets older!