They don't look like cubes to me. If you intend to hunt wild mushrooms, please educate yourself of various methods of identifying mushrooms. Do they bruise blue? Does the stipe have a ring around it (I don't see one in the pictures)? Did you take a spore print? What do the gills look like? Does the habitat you found them in match the conditions required for P. cubensis?
Many species of mushroom look very similar to the untrained eye, and some of them can be very poisonous. Get reading, and happy hunting! :thumb_up: