Can Anyone Tell Me What This Plant Is?

[Doughboy]

I am smart enough to know it's some sort of Lily, a relative of the Calla Lily I would say, but I have no idea what kind. The bloom is huge on it, probably over a foot long and a deep purple. The leaves are very large and very few, I think there are like five on it. The plant is in the yard of a vacant house that I do yard work for and the owner is long gone and I have no one else I can ask that knows plants.

[John Cuthber]

Looks like it might be this