Yep, this was a planned prequel film from DisneyToon Studios. According to Flavorwire, "It would have explained how the seven dwarfs met and how the Queen killed Snow White’s father to take the throne." However, a later pitch apparently had the story showing how Dopey lost his voice after witnissing his mother's death. John Lasseter cancelled the project in 2006.
#11 Catfish Bend
This film would've been based on the Catfish Bend book series by Ben Lucien Burman. A brief synopsis for the first book reads, "Caught in a Mississippi flood, a group of animals takes over the problem of flood control from the incompetent humans." Disney did acquire the rights, however, the project just never got greenlit and remained shelved (and eventually was given up on).
#12 The Three Pigs
Disney Feature Animation actually optioned the children's book of the same name by David Wiesner, back in 2002. The story, of course, is a retelling of the classic fairy tale. And then, in 2003, Disney announced that writers had been attached and the film would be a combination of computer and traditional animation. However, there's no clear explanation why the project was scrapped.
#13 Where the Wild Things Are
Way back in 1983, John Lasseter and animator Glen Keane (Beauty and the Beast, Pocahontas, Tangled) did an early CG experiment using Maurice Sendak’s iconic book as their subject matter. This test film was as far as an adaptation went, though, and then Universal acquired the rights in 2001 and, as you probably know, it became a live-action film instead.