Is there any site were I can download tiles from Snes games like Secret of Mana?

Well the art is copyright and using it in a game that you distribute in any way could get you sued but try putting using the terms "sprite", "rip", "rips" along with "snes secret of mana" into google (Try without secret of mana first, you might be able to get a link to one of the webrings).

try the following link
http://www.eagleeyerpg.com/2000tiles.html