Originally in ancient times 來来，which is a pictograph, means wheat, later another part was added to it, which made the new word 麥麦， in order to make difference from the verb 'come', which had borrowed the sound and shape of 來，来。 Simillarly, 牟, which originally meant the sound made by cows-- moos, later the sound and shape were borrowed to mean barley. In order not to cause confusion, moo and barley in ancient Chinese are respectively written/scribed as 哞 and 麰. Here is an example for 来and牟 in ancient Chinese, which respectively meant 'wheat' and 'barley'. 贻我来牟,帝命率育。——《诗·周颂·思文》

no

麰 is a kind of crop. 麦 has some means.one of means includes 麰. 牟 and 麰 have same pronunciation. but 牟 have another pronunciation “[mù]”