Whatever it it, it must have Godwin's The Cold Equations, Asimov's Nightfall, and Heinlein's It's Great to Be Back.
psik
I got curious and it seems no anthology has all three but, if two and a half outta three ain't bad:
The Ascent of Wonder: The Evolution of Hard SF (1994), ed. David G. Hartwell & Kathryn Cramer has "The Cold Equations" and "It's Great to Be Back" and makes up for the omission of "Nightfall" by including Asimov's "The Last Question," as well as his "Waterclap" and "The Life and Times of Multivac."
The Science Fiction Hall of Fame, Volume One (1970), ed. Robert Silverberg has "The Cold Equations" and "Nightfall" and makes up for the omission of "It's Great to Be Back" by including Heinlein's "The Roads Must Roll."
Modern Science Fiction (1974), ed. Norman Spinrad and
A Science Fiction Reader (1973), ed. Harry Harrison & Carol Pugner also include the two, but no Heinlein at all. (In fairness, both were originally paperbacks and (IIRC - maybe remembering wrong) Heinlein (or his associates) had odd reprint policies, so maybe they didn't have a choice. Still, the Harrison does not look especially good and the Spinrad, while excellent, mostly enjoys the softer side.)
Interestingly, no anthology includes "Nightfall" and "Back." If you substitute SFHOF's "Roads," then
Adventures in Time and Space (1946, aka
Famous Science-Fiction Stories), ed. Raymond J. Healy & J. Francis McComas and
Great Science Fiction Stories (1964), ed. Cordelia Titcomb Smith also qualify. Neither include "Cold," but
Adventures couldn't, being eight years too early. It very likely would have if it could have. Smith doesn't have that excuse, though.
I'd say the
SFHOF and
Adventures and, with reservations,
Ascent all qualify and, also with reservations, maybe even
Modern SF.