Mohenjo-daro: Seal: M-863 a: Sayid Ghulam Mustafa Shah and Asko Parpola, 1991: Corpus of Indus Seals and Inscriptions: Volume 2: Page 79: Collections in Pakistan: Suomalainen Tiedeakatemia.
There is only one extant example of this Indus sign.
This is Mahadevan's sign number 291, which I have redrawn to better reflect the original.
Wild Barley: Lynn Fawcett, 2017.