dove's dung

Boyd’s Bible Dictionary:

Eaten as a last resort, in time of famine (2 Kings 6:25).

Concise Bible Dictionary:

Some take this in 2 Kings 6:25 to represent a kind of herb; we have plants similarly named, as cowslip, hart’s-tongue, and the Arabs have a herb they call “sparrows’ dung.”

Strong’s Dictionary of Hebrew Words:

Transliteration:
dibyown
Phonic:
dib-yone’
Meaning:
in the margin for the textual reading, cheryown {kher-yone'}; both (in the plural only and) of uncertain derivation; probably some cheap vegetable, perhaps a bulbous root
KJV Usage:
dove's dung