Collecting and publishing mystery short stories in anthologies to benefit a charity is pretty common these days, with well over a dozen (of those I'm aware of) appearing just in 2013. I think it's a terrific idea, but when I searched back through the years, I didn't find that many such anthologies available. The recent boom is no doubt due to the rise of ebooks, since prior to the new digital era, print short story anthologies were considered a hard sell.
One of the earliest I could find was The Plot Thickens, which was edited by Mary Higgins Clark back in 1997 to benefit the adult literacy organization Literacy Partners. Contributing authors include Lawrence Block, Edna Buchanan, Carol Higgins Clark, Mary Higgins Clark, Lauren and Nelson DeMille, Janet Evanovich, Linda Fairstein, Nancy Pickard, Ann Rule, Donald E. Westlake, and Walter Mosley. Each story had to include a tale that features a thick fog, a thick book, and a thick steak, although everything else was fair game.
- "How Far it Could Go" by Lawrence Block is a conservational story set in a restaurant where a woman is interviewing a man she want to hire to intimidate her ex-boyfriend who says she owes him money;
- "Foolproof" by Edna Buchanan centers on the autopsy of an Egyptian mummy that reveals the supposedly thousand-year-old corpse was a murder victim with the same fingerprints as an infamous gang member;
- "Too Many Cooks" by Carol Higgins Clark is about an aspiring young actress in a steak sauce commercial where a series of puzzling accidents start happening on the set around her;
- "The Man Next Door" by Mary Higgins Clark finds a young woman kidnapped by her creepy neighbor, who happens to be a serial killer, via a shared basement;
- In "Revenge and Rebellion" by Nelson & Lauren DeMille, a woman entrusts her prized autobiograhical manuscript to an old college friend-turned literary agent, but doesn't take his criticism too well;
- "The Last Peep" by Janet Evanovich is a story featuring the author's iconic bounty hunter, Stephanie Plum, who's on the trail of a peeping tom exhibitionist, only to have her discover the man's dead, naked body—which promptly disappears;
- "Going Under" by Linda Fairstein focuses on an ambitious young policewoman who goes undercover as a dental patient to catch a molesting dentist;
- In "Thick-Headed" by Walter Mosley, the author once again manages to pack a complicated mix of colorful characters like gangsters, pimps, prostitutes, and two friends in trouble into a tight tale;
- "Love's Cottage" by Nancy Pickard is a fictionalized timeline of events surrounding the fatal fire and murders at Frank Lloyd Wright's Taliesin studios in Wisconsin;
- "The Road Trip" by Ann Rule follows a new divorcée on a road trip hoping to get away from her jealous ex-husband for awhile, only to find herself face to face with an infamous serial killer;
- "Take it Away" by Donald E. Westlake is an example of the author's trademark humor and charm, in which a hapless FBI agent on a stakeout is sent to get food for the team from the local Burger Whopper and strikes up a conversation with the man next to him in line, which takes a strange turn.
Both "The Man Next Door" by Mary Higgins Clark and "Take it Away" by Donald E. Westlake were chosen to be the Best American Mystery Stories 1998, edited by Sue Grafton.