This digest-size anthology reprints stories from DC Showcase #34 , House of Secrets #92, Detective Comics #359, Adventure Comics #269, Green Lantern #10, Adventure Comics #210, More Fun Comics #67 , Adventure Comics #256, and Adventure Comics #262. Writers include Gardner Fox, Len Wein, Robert Bernstein, John Broome, Otto Binder, and Ed Herron. Artists include Gil Kane, Bernie Wrightson, Carmine Infantino, Ramona Fradon, Curt Swan, Jack Kirby and Lee Elias. The cover is by Ross Andru. The back cover features the superheroes and the titles of their stories.
My favorite is the Swamp Thing story. This is the first version Len Wein and Bernie Wrightson created in 1971, which later became the basis for the long running Swamp Thing comic, rebooted in 1972*. Here is the original short story.