I have a red lid that I use. You can use anything or the rock. It's good for them to eat on a rock or concrete because it wears their beak down naturally as they eat.
Romaine occasionally, collard greens, kale occasionally, escarole, endive, raddichio, broccoli "dust" just the tips occasionally, dandelion greens, then all kinds of weeds and grass from the yard chopped up. .The Mazuri is all that is needed for sure but I mix it up and chop it pretty fine in both directions so every bite is easy to swallow.