Have you ever had the frustration on spawning item entities? or maybe you just don't know how?
Well you too can do this also!
All you need is a command block and a button and we can get crack'alackin!
First Type in this: ;
/summon Item X Y Z
Now Item is the entity id for dropped items.
In replace of the X Y Z are the coordinates where it is gonna be spawned in.

Next:add in this tag:
{Item:{id:#,Damage:#,Count:#}}
Inside the #s you need to put in your value of each specific tag.
id = the item id of the item you want to spawn
Damage = the value of it either being damaged or has counterparts of its self.
(Note:Item Damage refers to Equipment and Tool, as for Damage Data Value refers to counterparts of the item you are spawning.
e.g.A mob head has 5 counterparts so you need to use the Damage Value into either 2,3,4 or 5 to get the respective mob head you want.)

Now that you have input all of the commands together it should look like this:
/summon Item X Y Z {Item:{id:#,Damage:#,Count:#}}

again just input you values to their respective places.

now put the button on and activate and it should work!

One thing:you can also add in some extra tags like custom names,attributes and etc., but you have to figure that on your own!

If you can't i'll do a later tutorial for this kind of spawning.