I've had a bit more time to look at your message properly...
I had not realised that there were two Edwin Fulcher Hiscockses!
Your Edwin is the nephew of my ancestor. I had not spotted him before, because in the 1881 census he seems to be down as Edward. My Edwin is another son of Henry Charles H.
Had you seen the entry in the IGI, which must be for your Edwin?
Edwin Fulcher Hiscock [the s is missing - as it is also for my ancestor in 1881 census] married Grace Belle Smith at Samuel Smith's, Near Lewis, Cass, Iowa, US on 27 October 1898.
I had been puzzling over this, as my 2-greats grandfather was in his fifties by then, with wife and several children, and it did seem unlikely that he'd upped sticks to the colonies - but the similar name had to be connected.
I have a good deal of ancestry for Martha Shaw - she was a cousin to my Edwin's wife (Jane or Jenny Whittle), so if you are descended from the Iowa Edwin, you and I are cousins twice over.
E-mail me off-list & I'll send you what I have: firstname.lastname@example.org
Is the Eliza Hiscocks you have the Eliza who was sister to your Edwin? Or perhaps his daughter in America?
Have you seen Henry Charles Hiscocks's entry in the 1881 census? He had two grandsons living with him, both aged ten (twins?) and born at Duckington - presumably HWH's youngest sons. There are also Hiscocks living at Osborne Cottage on the Isle of Wight, which is next door to Osborne House, Queen Vic's "small holiday home" - coincidentally, it's only 20 miles or so from where I live in the New Forest.