Broccoli Seeds
Plant in the fall. Takes 8 days to mature, and continues to produce after first harvest.
Overview
Broccoli Seeds are a type of seed that can be planted to grow Broccoli. They are a relatively uncommon seed item and cannot be purchased from any traditional store. Instead, they are obtained through a variety of special sources, including digging up Seed Spots, completing Raccoon requests, trading at the Raccoon Wife's Shop for 5, using the 
Most of these sources only produce Broccoli Seeds during the Broccoli season window, from Summer 21 through Fall 20. The main exceptions are the Raccoon Wife's Shop trade and the Seed Maker, which are not restricted by that seasonal availability. This makes the seeds most convenient to stockpile when they are in season, while the off-season sources provide a way to obtain them later if needed.
Broccoli Seeds can be used for dyeing but not for tailoring. At the dye pots in 

Official description
Plant in the fall. Takes 8 days to mature, and continues to produce after first harvest.