Definitely not that recent, Keiva. [Keller] My own sister roasted a huge Thanksgiving turkey, only to be stood up by another sister and her spouse, leaving sister #1 to eat the "mother of a turkey".
Agreed that that phrase is older (and I believe it's a polite abbreviation for mother-f*cker), meaning "one hell of a big-'un".
But I don't think it's the same as "the mother of all _____". For example, your neighbor might also have another mother of a turkey on his table, another big-'un. That is, several turkeys could be "a mother of a turkey"; none is unique. In contrast, "mother of all wars" implies (to me) a unique war, unlike any other. Thus, one speaks of "a mother of a turkey", but "the mother of all wars".
