I'll see your Yummy and raise you a "Billy Don't Be A Hero" by Bo Donaldson and the Heywoods, who truly were one-hit wonders.
“Yummy, Yummy, Yummy, I’ve Got Love In My Tummy" was by the Ohio Express and doesn't count as a one-hit wonder. Although the Ohio Express was a group of studio musicians and the line-up changed from recording to recording (as was the case with most of the bubble gum bands), the Ohio Express had five Top 40 songs.
Not even 7 a.m. here and my useless knowledge about pre-1980 popular music is washing over me.
How could I have forgotten that one? But, I’m trying to now...