I didn't do much, if any, QSLing early in my listening career so I don't have much reference material to look back on. But I pretty vividly remember my first shortwave pirate being Radio EXP, probably on 7415 KHz AM and early on what was likely a winter Sunday morning. Probably 1990, perhaps 1989. This station was mentioned in Andy Yoder's books of the era but little comes up in Google. I think the announcer's name was Dr. Blue or something like that.
Right around that time, thanks to Andy's books, I was also looking on mediumwave but with much less success. To this date, the only hobby pirate I've heard on mediumwave was a station that ID'd as WORM on or about 1620 KHz playing the Doors. Same timeframe, about 1990. Never saw this one reported anywhere else.
This was the dawn of a pretty active SW pirate radio era and it was a good time, from 1990 until about 1994 when I dropped out of the hobby for about 10 years.