How much is an 1850 Morgan Head Liberty Silver Dollar worth?

There is no such coin. Morgan dollars* were not issued until 1878.

If you have a Liberty Seated dollar with that date, its value depends on its condition and mint mark:

No mint mark - $400 if very worn, $1000 if moderately worn, $1600 if like new

"O" mint mark - $250, $750, $1200

If you have a Morgan dollar with the date 1850 it is a counterfeit.

(*) The coin is called a Morgan dollar after its designer. It carries the image of Miss Liberty, not the head of Mr. Morgan.