Hi Dave
The entry for the birth of Samuel in
Irvine in the online IGI has been added by an LDS member. As has the 1841 Kirkoswald entry.
I checked the 1851 census index and there are no possible entries for your Samuel. Interestingly there is a Samuel in Kirkoswald living with either parents or brother, you will need to look at the full entry to find out which.
1851 Kirkoswald ED: 16-5
Daniel
MUIR 35y
Jean 2y
William 3m
Thomas 27y
Thomas 6y
Catherine 3y
Margaret 1m
Samuel 15y
It is odd that Samuel did not list his parents names when he married in 1861, either he did not know or is hiding the information for some reason.
Your next option is to research further in the States for more information about Samuel. Wills, obits, newspaper articles, headstone, census records etc.
You may also want to try a wider geographical search at Scotlands People in the 1861 census for Samuel.
tata
Alex