Found this Naturalization Record:
"Illinois, Northern District Naturalization Index, 1840-1950," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:XKLP-TVZ : 2 March 2021), Martin Haloden Magnus Fjeld, 1910; citing Illinois, NARA microfilm publication M1285 (Washington D.C.: National Archives and Records Administration, n.d.), roll 54; FHL microfilm 1,432,054.
And this with "M" for Morten.
The National Archives of Norway-Arkivverket; Norway; Church Books 1815-1960; Reference Number: SAO/A-10872/F/Fa/L0001 Norway, Church Records, 1812-1938 [database on-line]. Lehi, UT, USA: Ancestry.com Operations, Inc., 2020.
Morten Halfdan Magnus
Gender: Mannlig (Male)
Baptism Age: 0
Record Type: dåp (Baptism)
Birth Date:16 nov 1884
Baptism Date: 4 jan 1885
Baptism Place: Petrus, Oslo, Norge (Norway)
Baptism Municipality: Oslo
Father: Peder Pedersen Fjeld
Mother: Olava Bredine Hansen
https://www.ancestry.com/sharing/25211868?h=a24e4b&utm_campaign=bandido-webparts&utm_source=post-share-modal&utm_medium=copy-url This url does not need an Ancestry subscription.
Norway Census
"Norway, Oslo Census, 1901", database, FamilySearch (https://www.familysearch.org/ark:/61903/1:1:DMMF-Q1W2 : 11 November 2020), Halfdan Fjeld in entry for Ragna M. B. Fjeld, 1901, Kristiania, Norge
And New York Arrivals Passenger List
Martin Fjeld
Gender: Male
Ethnicity/ Nationality: Scandinavian
Age: 19
Birth Date: abt 1884
Departure Port: Christiania
Arrival Date: 16 Jun 1903
Arrival Port: New York, New York, USA
Ship Name: United States
https://www.ancestry.com/sharing/25211993?h=dac2c0&utm_campaign=bandido-webparts&utm_source=post-share-modal&utm_medium=copy-url No subscription needed.
Note: His Naturalization record states he arrived 1905 after Verner's birth, but seems he was wrong. Departure was from Christiania/Kristiania where he was residing in 1901.