Do you know variety that is? Mine is called “Jack’s Giant”.
They both look similar to the Taro plant grown in many South Pacific Islands, the root tubers and the leaves are a food staple on most. BUT DON’T EAT THE LEAVES RAW! Cook them thoroughly.
Nope. Two answers that boil down to same-same. First, there are some on next [undeveloped] parcel so maybe they are native. Second, this parcel is considered to be an “old garden” so many things were planted. We have little idea what, let alone variety. Possible exception being the bamboo that is a junky timber variety, we think called OldHam.
The idea of edibility is intriguing to me. I’m trying to grow enough cabbage or equivalent to supply our friendlty local widow. One leaf would be like a whole head of cabbage 
Look up the recipe for Taro leaves, I’ve had Taro leaf and they’re not bad, the closest thing in taste is probably collard greens but with the cooked leaves have a texture more like spinach or beet greens. The root of the plant has a consistency and taste very much like tapioca.
The reason for not eating them raw is because they have some kind of crystalline structure that causes inflammation and burning in the mouth and throat.