Few modern collectors know of the Nu-Card company, who made a handful of sport sets in 1960 and 1961. Both of their baseball issues ("Hi-lites" and "Scoops") feature a newspaper format with single-game "stories," a mix of retired and active players, and trivia questions on the back.
Nu-Card probably chose this unorthodox format--postcard size, black-and-white photos, no stats--to avoid legal problems with Topps, who reigned supreme over cards after buying out rival Bowman in 1956. The company turned out a few hundred cards (if you include 1961's college football) of decent quality across two years, so it's surprising they vanished without a trace. (Collectors might've wanted the color photos and statistic grids available in Topps, so didn't buy them.)
Many of the set's 72 cards point elsewhere in the set. Number five redirects this Yankee Stadium question to #50, which covers its longest recorded homer.
Mantle's homer hit Yankee Stadium's upper facade, a near-miss to leaving the park itself, a feat no player achieved in a regulation game.
An alternate black-and-white printing of this set covered just the first 18 cards, came with blank backs (eliminating the trivia questions), and carried the CVC copyright instead of NCI in the "newspaper" header.
Price guides report CVC cards as scarcer than NCI, but both cost about the same thanks to the variation's crudity and low demand for this set in general.
Value: You can find individual "hi-lites" for $5 and less, with some superstars running several times that.
Fakes / reprints: According to the SCD catalog, someone counterfeited the 1961 Nu-Card Scoops set (released the year after this Hi-Lites issue), but I haven't seen any faked 1960 cards in the market.