I am going to aim for the low hanging fruit first. I have tracked down a number of Blender tutorials that are current and relevant to newcomers to 3D design. I have followed each tutorial through myself to make sure it is clear and accurate and I have only picked the best and most concise. There is no point me re-writing all this info and leaves me more time to write about other topics.
http://www.raywenderlich.com/49955/blen ... a-mushroom
This first tutorial walks you through making a little Super Mario-esque mushroom. What is fantastic about this tutorial is it really covers all the basics. First understanding the layout, camera movements and control, then it moves on to manipulating objects, taking basic shapes and editing them, UV mapping and even painting the textures directly in Blender. Everything is clearly annotated and illustrated well with pictures. These are all universal skills you will need again and again.This tutorial covers the following concepts:
*Blender basic setup
*Adding and transforming objects in Object Mode
*Editing the object in Edit Mode
*Unwrapping the object’s UV mesh
*Creating a texture
*Exporting your files.
Remember you can deviate from the tutorial once you understand the principles involved. So you could also attempt to paint your mushroom in a realistic way instead. Or maybe try making some variations using the skills you learned in the "adding and transforming an object" and the "editing in "Edit Mode" sections. Try making the stalk longer, or giving the head a different shape.
There is a lot of info packed into that one, so I will leave this tutorial at that and leave the thread open for any questions you might have.
Best of luck!

IMPORTANT EDIT - I will assume that you have covered this in future tutorials.