If I let some of my radishes go to seed, how do I harvets the seeds to use again (rather than buying packets)?
Just let pods dry a bit(change color), pull them off the plant, dry them a bit more and then shell them.
If any of the pods shatter before you get them picked as farmerdilla suggests, the seeds will come up early next spring and give you early radishes in that area of the garden.
Thank you for reminding me, I have grown something called 'rat tailed radish' in the past. The green seed pods are eaten, tender when young. I have used the last seed I had so I'll let a few of the French breakfast go to seed to see if they will work instead.