Fertilizer Woman

Fertilizer Woman is an unmarked quest in Fallout 4.

Walkthrough
When visiting her in Vault 81, Dr. Penske asks the Sole Survivor to eat a fresh mutfruit from her farming to help her investigation. After eating it and talking to her again, she offers to buy bags of fertilizer from the player character for 25 caps each.

Bugs
When trying to sell fertilizer to Dr. Penske, she may just give generic dialogue instead.
 * Reverse-pickpocketing one bag of fertilizer onto Dr. Penske will resolve this, since the code erroneously checks her inventory to trigger the dialogue, not the player character's. Alternatively, the console command can be used to add a bag directly to her inventory without risk of being caught pickpocketing.