Pignuts?

We have several types of hickories on our place.   The tree that bore these is right on the path and it's obviously a hickory when you look at the leaves, but a good friend who really knows hickories told us that these aren't the 'real' hickory nuts.   So I gathered some up and did some research. 

Hickory is a large family of nut bearing trees in the genus Carya.  'Carya' is from an Ancient Greek word meaning nut.  

The hickory nuts that you like to eat are Carya lacinosa or Carya ovata.  
Pecans [Carya illinoinensis] are a type of hickory.
Pignuts [Carya glabra] are  hickories.
Bitternuts [Carya cordiformis] are hickories.  

Ours are either pignuts or bitternuts - not very tasty, they say.   Only the squirrels like them.