Potato leaves are poisonous. They are in the "Nightshade" family of plants. I believe that yam leaves may also fall into that category. Cooking them might make them edible for humans? I'm not certain, but don't feed them until someone who knows more chimes in........
I agree that sweet potato (Ipomea) leaves are fine. These are in the Morning Glory family (Convolvulaceae). True yams are not safe (Dioscoreaceae is that family).
Snow Pea leaves are fine in small quantities, mixed with other foods; they are high in oxalates.
Tong Ho is a name for garland chrysanthemum, and they are fine too. I know them more from their use in Japanese cooking as shungiku.I hadn't been thinking about including this in my feeding, but they look like a very healthy vegetable, rich in minerals. So, thanks.
As additional info, Snow Pea leaves have approximately 25% of the oxalates and 50% of the calcium as do dandelion leaves. I would have no hesitation feeding them as part of a varied diet.