Booster Gold guest stars in Superman #30 from DC Comics. Here's the official summary:
"Superman has found the mysterious hero known as Booster Gold. Together, they must return to the present day to warn the Justice League, but Darkseid’s Legion stands in the way. The shocking events of this issue lead into next month’s massive next chapter in the all in saga!!"
The sixth comic book in the Ollie's grab bag was L.E.G.I.O.N. '90 #17 (1990) from DC Comics and is a version of the Legion of Super-Heroes. The cover features Vril Dox, Strata, Lyrissa and Stealth. Lobo, Captain Comet and Lady Quark also appear in this issue. By the way, L.E.G.I.O.N. stands for Licensed Extra-Governmental Interstellar Operatives Network and the three founding characters first appeared in the three issue Invasion mini series, which I have read and still have. I have also read L.E.G.I.O.N. '94 #65 and 70, which is the last issue (the series actually started as L.E.G.I.O.N. '89 and was actually replaced with R.E.B.E.L.S. '94). The story is titled "The Power of Positive Thinking" and is a small piece of a bigger puzzle so I won't go into detail here but it was an interesting read.