What are the other sources of calcium for a kids besides milk and yoghurt?

Apparently, dark-green vegetables like kale, peas, broccoli, kailan and spinach are great sources of calcium. Spinach, especially, is known to be an awesome source of calcium for toddlers: 1 cup = 200mg of calcium! However, spinach also contains oxalic acid, which ironically, interferes with calcium absorption so don't just depend on spinach -- the other dark green veggies should be tried as well :)