Cockles of one’s heart

What is Cockles of one’s heart?

Cockles of one’s heart definition and meaning on Dictionary terms:
any bivalve mollusk of the genus Cardium, having somewhat heart-shaped, radially ribbed valves, especially C. edule, the common edible species of Europe.
any of various allied or similar mollusks.
cockleshell(defs 1, 2).

a wrinkle; pucker: a cockle in fabric.
a small, crisp candy of sugar and flour, bearing a motto.

verb (used without object), cock