Greenstang

Ya
I'm pretty good at picking up on things like that. Caught on right away. 

For my own information, what leads you to believe this a matte proof?

It looks to me like someone has attempted to polish it. You can still see dirt between the letters.

Hafta agree-
Sure looks like a crack to me.

Correct me if I'm wrong Just Bob, but are you insinuating that previous post is Spam?

Ya
I'm pretty good at picking up on things like that. Caught on right away. 

Nice
 Another good thing is that they are 90% silver.

What you really need to look out for is a 1982D Copper Small Date.
Now those are worth big bucks. Chances of finding one are pretty slim but still worth the look.

Welcome to the Forum Lykou7
First of all, you are in the wrong Forum, this Forum is for people with Registry Sets.
Perhaps one of the moderators can move it and help you with your photos. Without them there is not much we can tell you. Please make sure you shoot clear photos of both sides oriented up.  Looking forward to seeing what you have.
 

Sorry, not a die crack. It is damage from having been struck with something.

It's too damaged to be gradeable.

I agree with MarkFeld.
Nickel just has circulation wear and even increasing the size of the half, I can't see any signs of a die clash.
 

Welcome to the Chat Board-
Not an error, looks like fingerprint to me.
 

I can only go by what they are asking on eBay for these sets.
The 1975 Uncirculated sets (There should be two sets in each envelope) $8.-9.00 for each envelope.
The silver Ikes in the blue holders are $10.00 each.

There are two types of 1976 Ikes, 1 & 2. Yours is a type 1. (Type 2 is the more valuable.) Hard to see condition as pictures are blurry but unless in MS condition, not worth much over face value as there were over 117 Million minted in Philadelphia alone.

Here again you don't state what info you want. There were over 394 Million minted with the P Mint Mark.
It looks like it has taken a hit on the date damaging the second 0.
Value 5 cents

That is MD. Notice how the devices are reduced in size while the secondary image is flat and shelf like. 
A Doubled Die will show splits in the serifs (if any) with the devices being thicker showing rounded secondary images. 
Point of interest.
If you are looking for a Doubled Die in coins produced since the mid 90's, look for them in the centre of the coin. With the advent of the Single Squeeze Hubbing, only the centre of the coin will show a Doubling. The peremiter will nearly always show MD.
 

Welcome to the Chat Box
Nice Find, it's a planchet error called a delamination. The planchet had a lamination that appears to have fallen off before the coin was struck. There would be a premium but I'm not sure how much.
Nice photos by the way.

Aimee-
Your seeing something that is not there. What you describe is impossible to happen during the striking of the coin. please read this that I just posted  to another member who is asking the same basic question.
 

I don't know how you can read that as a 1949 D/S Nickel when you can't even see the MM if it even has one. There is so much damage in that area it is impossible to make out what is or isn't there. Here is a photo of the D/S MM to show you what it is supposed to look like.

Welcome to the Chat Box
Nice Find, it's a planchet error called a delamination. The planchet had a lamination that appears to have fallen off before the coin was struck. There would be a premium but I'm not sure how much.
Nice photos by the way.

The word cents and Jeffersons head is just damage. Whenever you see incuse marks that are not supposed to be there, it is nearly always damage. The rim also has been badly damaged. The coin does have some coin rotation but most collectors like to see a rotation of 180o, besides with the condition of the coin, any premium would be nullified.
Remember, it is only an error if it happens during the striking of the coin, anything that happens after that is just damage so whenever you see a coin with dings, gouges, scratches, flattened letters, misshapen letters or what appears to be extra numbers or letters etc. is probably just damage. There is no harm in collecting damaged coins, it's just that in most cases they are only worth face value.

A nice coin but not full steps and has some wear. Might be worth a couple of dollars.

The MM were hand punched until 1990 so they can be anywhere in that area. Yours is a little higher than normal but not high enough to be called the high MM

The fact that the hairlines go over the devices indicate that it was cleaned.
 If it was anything else, the hairlines would only be on the fields.