Nobody. The Church of Jesus Christ of Latter-day Saints (the "Mormon" church) was founded in the US - so the first Mormons were already in the US! :)
If you are speaking of the first Mormons to move from another country to the US, rather than the first Mormons ever in the US, the answer is still nobody. The first Mormons to move from another country to the US came from Canada, and were not 'brought' by any specific person, only encouraged to move so that they could be nearer to the main body of the church.
The ship Brooklyn.
horses became extinct in the us un'till columbus brought them back
Spain
The idea was said to originate with Gerald Gardner who brought it to the US in 1950's.
Jamestown, VA
In 1619,a Dutch ship brought the first 20 slaves to the English colony of Virginia.
when was the first car bought out
Charlotte Jackson.
Jamestown in 1620.
All states in the US are inhabited by mormons, Utah having the largest population.
The first Mormons left Nauvoo in February 1846.
The first modern horses in California were brought by the Spanish.The first cattle in California were brought by settlers on wagon trains from the US.