I don't have any myself, but I know of some. They both do them differently.
Peni here writes what comes off the top of her head.
While Minerrale takes prompts (there is a thread dedicated to these on the forum) and spins them into stories.
As Helio said there are many short story compilations on Tapas, and you can do it anyway you want. Bite-sized stories is what Tapas is about. If you're paying, i'm sure artists would be willing to work with you. I haven't seen a collaboration between writers, so I have no idea what to say on that, but there are some collaborations between writers and artists. They happen and some really good stories come out of them, so best endeavors.