When surveying a new world what do I need to check exists that I can't create later?

Question

I realised with my last world that when I came to build a bookcase there were no reeds (sugar cane) anywhere in the world even though they do exist in the game, so I started a new world and after exploring a few found one that did have reeds in it.

However, there may well be more items out there that need to exist right from the beginning of the world and I don't want to build my next gigantic mansion only to find I can't build 'X' because the ingredients aren't available in my current world.

In Pocket Edition is there a list of items that need to exist from the start in the world that you can't actually create later on?

Now that version 0.4.0 is released that has plenty more items available (foods, dyes, mobs...) so there are probably lots of items that I should be looking out for when choosing my new space.

Answer 1

Sugar cane, clay, cactus and mushrooms (both red and brown) are the rare things that I believe you will need to make a successful world. Do keep in mind, though, that your diamonds, gold, lapis lazuli, and even iron and coal supply is limited. Animals spawn randomly so don't worry if you cant see any.