Mm, nummy in my tummy! where does nummy come from Sense “idle, meaningless talk” (1940), probably imitative or echoic in origin From dictionary.com i found that nummy is a form of yummy, formed by.
Nummy Brand Design. on Behance
What is the origin of the word yummy, as in this food is yummy
All i can find are dates of known first uses.
Blah, as suggested by the wiktionary has an uncertain origin