“When less than four years old I was standing with my nurse, Mary Ward, watching the shadows on the wall from branches of an elm behind which the moon had risen. I have never forgot those shadows and am often trying to paint them.”

This quotation is often found on the internet attributed to Magellan, but never with a source, and no English occurrence prior to its use by Robert Green Ingersoll in his essay "Individuality" http://www.infidels.org/library/historical/robert_ingersoll/individuality.html (1873) has been located. Thus, it it most likely spurious. In that essay Ingersoll states:
It is a blessed thing that in every age some one has had individuality enough and courage enough to stand by his own convictions, — some one who had the grandeur to say his say. I believe it was Magellan who said, "The church says the earth is flat; but I have seen its shadow on the moon, and I have more confidence even in a shadow than in the church." On the prow of his ship were disobedience, defiance, scorn, and success.
Disputed
Variant: The Church says that the Earth is Flat, but I know that it is Round. For I have seen its Shadow on the Moon and I have more Faith in a Shadow than in the Church.
Source: As quoted in Oxford Academic (25 July 2013) http://oupacademic.tumblr.com/post/56463634957/misquotation-i-have-seen-the-shadow-of-the-earth

Nelly Dean (Ch. X).
Wuthering Heights (1847)

The Blind Owl

Source: Falling Upward: A Spirituality for the Two Halves of Life

The Killing Season, Episode three: The Long Shadow (2010–13)

Wolf Am I! (And Shadow).
Brother, Sister (2006)

Source: Sonnets from the Portuguese

I had no money. Just a Rucksack and a hammer. And I started these assemblages. That was in 1921, But in all books on assemblages these things are not mentioned.
Homage to the square' (1964), Oral history interview with Josef Albers' (1968)