These are not dinosaur eggs. They are septarian nodules, also called septarian concretions.
Have a read of this:
- http://en.wikipedia.org/wiki/Concretion (there is a section entitled 'Septarian concretions')
There is a lot of misinformation on septarian nodules, eg. http://www.bestcrystals.com/septarian.htm, http://www.madagascarminerals.com/metaphysic_of_septarian_physi.cfm
and much of the misinformation is copied between different sites.
Also, the word 'septum' has nothing to do with 'sept' meaning seven.
You have a very nice septarian nodule that looks like a dino egg, although it is not it still is a good specimen and rare.
The one that interests me is the one with the only image.
It is a pyritic nodule that could contain a fossil, infact a fossil collector has given it a 'tap' on the beach with his hammer trying to see what is inside, you can see the hammer marks on the side (brusess)
I have a similar septarian nodule and a pyritic nodule with ammonite inclusions that you should look for when collecting these nodules, please see images below.
'Dino egg' from the Holderness Coast and the pyritic nodule from the Whitby area.