Hello,
This discussion is a bit old, but I'm happy to join...
I don't have any pre-1920 team picture but I do have some Hull memorabilia to share...
Baines Card, Cyril Lempriere, Hull


Baines Card - Hull

Hull Stadium - Hull v Seaton - 1st round N.U.Cup - March 15th 1913

hi res picture:
http://farm7.staticflickr.com/6181/6106320591_1abf4322af_o.jpgHull Stadium - no date

hi res picture
http://farm7.staticflickr.com/6045/6233768706_378fa954fb_o.jpg
hi res picture
http://farm7.staticflickr.com/6204/6106866062_b41d1d13b5_o.jpgHull Stadium - 1921

hi res picture
http://farm3.staticflickr.com/2185/2413385627_444800b443_o.jpgHere's Hull "Hall of Fame" Billy Batten in 1928, with his son Billy Batten, Jr. Batten joined Hull in 1913 from Hunslet for a then-record £600 fee...
http://en.wikipedia.org/wiki/Billy_Batten
Finally, here's a portrait of Mr A.J.Boynton who was Hull FC chairman before ww1 (and after ?)

If you want to get a idea of how pre-ww1 Northern Union rugby was played, I can only recommend these wonderful video footages from 1901-02 (Mitchell & Kenyon collection, British Film Institute). Unfortunately Hull is not featured in these movies... but definetively worth a look ! (Hunslet v Leeds, Salford v Batley, Oldham v Swinton)
http://rugby-pioneers.blogs.com/rugby/2009/12/the-wolrd-oldest-rugby-videos-amazing-.htmlI'm mostly a Rugby Union collector, but you could "dig" into my Flickr collection
http://www.flickr.com/photos/rugby_pioneers/ for some old R.L./N.U. pictures (Baines cards, Hunslet, Huddersfield, Salford, etc...) if you like...
@+
Frederic
www.rugby-pioneers.com