What am I?

Can you guess what these riddles are describing?

I grow on a tree,
I have 4-5 edges,
I am juicy,
I have no pips or seeds,
I only grow in the Cook Islands,
I can come in very bright colours,
What am I?
By Harriet

I have a variety of colours,
I can be sour and sweet,
I have a stalk on top,
I am shiny and smooth,
What am I?
By Paige

I am hairy,
I am brown as mud,
You eat me with a spoon,
I am green on the inside,
What am I?
By Jasmine