Once I Was On Creative 1.7.4 And I Had Cheats On.  So First You Go On Commands And Do

/summon EnderDragon

Then He Will Come And Break Everything So Do It In A New World Because He Breaks All Block Expect Bedrock.
The Next Command To Get Player Heads Is

/give playername 137 1 3 {SkullOwner:"playername"}


Where I Put playername You Put Your Nameatag Like For Exaple My Nametag Is

chicrab So I Would Put

/give chicrab 137 1 3 {SkullOwner:"chicrab"}

It Might Not Work On Any Version Higher Then 1.7.4

Thx For Reading