Raw Material

From the short story "Raw Material" by A.S. Byatt, appearing in The Atlantic in 2002, before they stopped doing fiction.

The protagonist teaches writing classes.

"In fact he had tried unsuccessfully to sell two different stories based
on the confessions (or inventions) of his class. The students offered
themselves to him like raw oysters on pristine plates. They told him
horror and bathos, daydreams, vituperation, and vengeance. They
couldn't write; their inventions were crude, and he couldn't find a way
to perform the necessary operations to spin the muddy straw into silk,
or turn the raw, bleeding chunks into a savory dish. So he kept faith
with them, not entirely voluntarily. He did care about writing. He
cared about writing more than anything—sex, food, beer, fresh air, even
warmth. He wrote and rewrote perpetually in his trailer. He was
rewriting his fifth novel. Bad Boy had been written in a rush
just out of school and snapped up by the first publisher he'd
sent it to. It was what he had expected. His second novel, Smile and Smile,
had sold 600 copies, and was remaindered. His third and fourth,
frequently rewritten, lay in brown paper, stamped and restamped, in a
tin chest in the trailer. He didn't have an agent."

available online at Raw Material by A.S. Byatt