I have the same problem. I always say I have duck feet.
Blundstone Style #200 run wider than the regular Blundstones. That’s what I’m wearing right now.
http://www.blundstone.com.au/mens-or-womens-chestnut-brown-work-and-safety-boots-style-200
Redbacks are better quality than Blundstone, IMO, and also run wider than the regular Blundstones. My last pair was Redbacks and my next pair will be, too.
http://www.redbackboots.com/ecommerce/redback-australian-workboots/easy-escape-black.cfm
Be aware that the sizing on Australian boots is in whole size increments only: 5, 6, 7, etc. The half sizes are the same length as the whole side, just wider. In regular shoes, I wear womens size 7.5 or 8, extra wide (EE) and wear 5.5 in the Australian boots.
Some of the Justin boys/mens styles come up to EEE width. I wear a 6EE in those. The Sheplers web site lets you search by size:
http://www.sheplers.com/mens-cowboy-boots.html
Finally, women’s Ariat Terrains run wide and some colors/styles also come in wide. I’ve got a pair of these in 7.5 W that fit well, but are, admittedly, none too wide.
http://www.ariat.com/TERRAIN_W_FOO.html?dwvar_TERRAIN__W__FOO_color=TAUPE#sz=12&start=16
If the Ariat RT are too narrow, they may not fit you because I can wear the Heritage RT, although only with thin socks and no wiggle room.