What is the meaning of this rebus?

marcus Brutus
john wilkes Booth
Billy the kid
Bonnie parker
clyde Barrow

Black as night I can be,
Until my Mother sits on me;
Then clear as ice I become
In the rough, thank you Mum.

What am I?

Each of the following sentences contains clues to a set of three words that are spelled the same, except for one letter (each sentence describes a different set). Example: malt, melt, molt.

1) Billy discovered a cylindrical chest buried beneath the knoll.

2) The only evidence found by the detective was some adhesive in the chimney passage.

3) The bashful bovine rested on the small bed.

4) The latest fad was for people to desire the ...

Each of the following sentences contains clues to a set of three words that are spelled the same, except for one letter (each sentence describes a different set). Example: malt, melt, molt.

1) The subject of the meeting was "The Poisonous Elixir".

2) When the man refused to fight, it caused the bully to shout "Are you chicken?".

3) When the cows heard the snake shake, there was a fight for survival.

4) Unable to see, the doctor was still ...