cockle (n.1)

type of edible European mollusk, early 14c., from Old French coquille (13c.) "scallop, scallop shell; mother of pearl; a kind of hat," altered (by influence of coque "shell") from Vulgar Latin *conchilia, from Latin conchylium "mussel, shellfish," from Greek konkhylion "little shellfish," from konkhē "mussel, conch." Phrase cockles of the heart "inmost recesses of one's spirit" (1660s) is perhaps from similar shape, or from Latin corculum, diminutive of cor "heart." Cockle-shell attested from early 15c.

name of flowering weeds that grow in wheat fields, Old English coccel "darnel," used in Middle English to translate the Bible word now usually given as tares (see tare (n.1)). It is in no other Germanic language and may be from a diminutive of Latin coccus "grain, berry." A Celtic origin also has been proposed.