Can you post a close up of the plant in question?

Here is a larger pic of the begonia in question, hope this helps....Its the really BIG one!

Here is a link that might be useful: Big Begonia Close-up

I assumed that was the one you were talking about. Now can you get a picture of the top of the leaf or several leaves? It's hard to ID by looking at the under side of the leaves. The only thing we have to go by now is size and leaf shape.

Here are some more pics that could help. The plant in the original pics are of one my mother used to have when I was young so I cannot show a close up, it has been dead and gone for many years. I have never been able to find one until recently and I'm hoping that the new plant is the same species as my mothers. The pics I am posting now are of the plant I bought this summer.

Here is a link that might be useful: Close-up of new plant

The new begonia looks like some form of ricinifolia (there are so many hybrids of this). The first begonia you posted based on the leaf shape looks similar to 'Sunbar' or 'Suncana' but without more pictures or the actual plant it is hard to tell.