Weird Eggs

I am sure the answer is in these threads somewhere but I can't find and answer so here goes. I got 2 db & 2 jg hens from a neighbor. They both have been very slow in the egg department but thats ok, the others give us enough eggs for eating. When I first got the new ones, I found a leather egg out in the yard that we have penned in for them. I think it was the db that laid it there. Then last week I got a weird looking egg that it seems like the shell is very thin in spots and is very long, then a couple days later, I got another one and then today I got a third one. It looks like they have calcium build up on the pointed end and is thin in the middle. They do have access to oyster shell also so I don't know what else would cause this. They also get layer feed along with garden veggies, bread and crackers. Is there something I am doing wrong? Has anyone esle had this problem? The eggs are fine on the inside, we have been giving them to the dogs mixed in thier food. Here is a link to the pictures of the three eggs in question. I am pretty sure it is the db that is laying them.
http://picasaweb.google.com/nhnanna/2008_0815WeirdEggs

Any help will be greatly appreciated.

 

I don't think that these girls are first time layers. I think the neighbor said they were about two years old.