Hope you'll stop back and post again here in your thread re. Matthias Larsen Sletten.
This seems to be the family (?) posted by Brian:
"Lars Olsen, født ca 1794, gift 1. gang 16. april 1816 som ungkar, dragon på Båbergseie med tjenestejente på Udal, Kari Pedersdtr. født ca. 1792 i Båbergstuen. I 1818 er de husmannsfolk på Gullordsletten under Øvre Gullord. De fikk flere barn, og Kari døde i 1837. Lars gift 2. gang 1838."http://forum.arkivverket.no/topic/115736-30142-husmannsfolk-...
Here is an Ancestry message board post from 2007:
"My Ancestor Mathias Sletten came to the US in 1847. He "reportedly" arrived with several brothers. They were from Berepresthjill, Norway and their father's name in Norway was Lars but on arriving they were told that Larson was such a common name that Mathias took Larson as a middle name and the brothers changed their name to Sletten. They first went to IL and from there they reportedly split up and went to find land to settle. (Some reportedly went to TX) Mathias was one of the first settlers of Martell, WI settling there by 1850. He married Bertha Thoen in 1854. According to church records they had 8 children but only 4 survived to adulthood. Mathias served in the Civil War and in 1871 they moved to Erhard, Otter Tail Co., MN....had a son Martin b. 23 Sep 1864" Info added: Mathias died June 1902 in Velva, McHenry, North Dakota.http://boards.rootsweb.com/surnames.slaten/110.1.1/mb.ashx
The above is an old post and obviously the OP has cleared up the place name.
Berepresthjill probably = Biri Prestegjeld
Martell is in Pierce county, Wisconsin
(One wonders what is the source of those locations and the other info - where did jm read or hear each piece of information)
I won't try to research this, as highly capable people are already "on the case."