Please identify, I am in Eastern North Carolina...thank you

so helpful to me! Have a great weekend

Tall seedling thought to be some kind of “prickly pear”? If I am correct does anyone know if it is an eastern, cold hardy type? Also, the small cacti coming in, are they the lovely saguaro cactus? Slow growing aren’t they? Please, if known give species and genus. Thank you and have a great weekend. ...

I understand that this cacti is commonly known as a “brain cactus”. Is this the common name and can someone give me the species or Latin name. Truly, I am in uncharted territory and so the species, genus, Latin, or otherwise is at the moment “all greek to me”...ANY information appreciated and any gr...