Beheaded, I am a portion of land.

Beheaded again and transposed, and I become the lot of all humanity.

Answer: Chide, hide, die.

Complete, I am without rule or method.

Beheaded and transposed, I am a mythological true friend;

Again, and I give expression to sounds of grief.

Answer: Random, Damon, moan.

My whole is a metal.

Beheaded, curtailed, and transposed, I am a noted English poet.

Beheaded and transposed, I then become an American poet.