A unitary fastener for joining a top element and a deformable bottom element face-to-face, the fastener comprising: a head including a cone-shaped flange being the largest diameter of the fastener, said flange having an uninterrupted circular periphery adapted to resiliently deflect upwardly; and a shank extending immediately downward from said head, said shank having one of (a), (b), and (c) as follows: (a) attachment means including: a collar immediately downward from the head; and an undercut immediately downward from the collar and adapted to receive the cold flow of material from the deformable bottom element, the largest diameter of the undercut being smaller than the diameter of the collar; (b) attachment means including: a collar immediately downward from the head; and a helically threaded shaft adapted to receive the cold flow of material from the deformable bottom element, the largest diameter of the shaft being smaller than the diameter of the collar; and (c) attachment means including a helically threaded shaft immediately downward from the head and adapted to receive the cold flow of material from the deformable bottom element. a head including a cone-shaped flange being the largest diameter of the fastener, said flange having an uninterrupted circular periphery adapted to resiliently deflect upwardly; and a shank extending immediately downward from said head, said shank having one of (a), (b), and (c) as follows: (a) attachment means including: a collar immediately downward from the head; and an undercut immediately downward from the collar and adapted to receive the cold flow of material from the deformable bottom element, the largest diameter of the undercut being smaller than the diameter of the collar; (b) attachment means including: a collar immediately downward from the head; and a helically threaded shaft adapted to receive the cold flow of material from the deformable bottom element, the largest diameter of the shaft being smaller than the diameter of the collar; and (c) attachment means including a helically threaded shaft immediately downward from the head and adapted to receive the cold flow of material from the deformable bottom element. (a) attachment means including: a collar immediately downward from the head; and an undercut immediately downward from the collar and adapted to receive the cold flow of material from the deformable bottom element, the largest diameter of the undercut being smaller than the diameter of the collar; a collar immediately downward from the head; and an undercut immediately downward from the collar and adapted to receive the cold flow of material from the deformable bottom element, the largest diameter of the undercut being smaller than the diameter of the collar; (b) attachment means including: a collar immediately downward from the head; and a helically threaded shaft adapted to receive the cold flow of material from the deformable bottom element, the largest diameter of the shaft being smaller than the diameter of the collar; and a collar immediately downward from the head; and a helically threaded shaft adapted to receive the cold flow of material from the deformable bottom element, the largest diameter of the shaft being smaller than the diameter of the collar; and (c) attachment means including a helically threaded shaft immediately downward from the head and adapted to receive the cold flow of material from the deformable bottom element.