Blanche spinach, try not to eat them raw. Speaking of oxalates, I did not know yam leaves were inedible. Saw a little tender shoot, bit a little piece off. Tastes like mushroom. I don't think it's toxic but it's like eating glass.
And that "eating glass" comment is related to how I know. I boiled a wild "edible" (skunkweed leaves) in 3 changes of water; what I should have done is either dry it completely or (better) treat it with lye. Bad memory mistake. Yeah: eating glass shards.