Help needed with a pickup script

You need to set the type of your variables, it isn't crucial to the problem but important for the future.

 var addmat1 : int = 5;

You're not using the variable returned from the collision.

 function OnTriggerEnter (Collision: Collider)
 //Should be
 function OnTriggerEnter (other : Collider)
 //As this is the data from the other colliding object, not the collision
 //Then use
 if (other.GameObject == collide1) {
     //As garner stated do not end the if-statements with semicolon
 }

You might as well use the colliders as variables instead of calling the GameObjects if you don't plan on using the reference later.

 var collide1 : Collider;
 if (other == collide1) {}

I recommend you to start using #pragma strict in the top of your scripting documents to disable dynamic scripting, you will have a much easier pipeline for errors, and the main reason, much faster code.

Although when creating pickups it's usually better to let the pickups have values that passes on to a handler. So if you'd create a pickup-script and attached it to the GameObject, then you'll be able to give it different amounts of values, for instance a pile of gold is more worth than a single gold coin but increases the same value.

You could start off with an enum setting the type of pickup, then give that particular pickup a value.

 enum PICKUP {
     Nails,
     Wood,
     Metal,
     Misc
 }

 //From the inspector you can switch this and make the object into a prefab
 var pickupType : PICKUP = PICKUP.Nails;
 var amount : int = 1;

Now when the collision occurs you can ask the colliding object what it is and how much it is worth.

 function OnTriggerEnter (other : Collider) {
     if (!other.CompareTag("Pickup")) return; //Make sure that this is a pickup else exit (needs a tag set in the Inspector)
     var pickupScript : PickupScript = other.GetComponent(PickupScript); //Get the script from the colliding object
     DoSomething(pickupScript.pickupType, pickupScript.amount); //Send the type and amount into a function
 }

 //Take care of the amount that should get stored into corresponding variable
 function DoSomething (type : PICKUP, amount : int) {
     switch (type) {
         case PICKUP.Nails: mat1+=amount; break;
         case PICKUP.Wood: mat2+=amount; break;
         case PICKUP.Metal: mat3+=amount; break;
         case PICKUP.Misc: mat4+=amount; break;
     }
 }