That’s a good question! I suggest you look on eBay or a similar site as thousands of buttons have changed hands at auction for whatever the buyer thinks is the right price. Thousands more have probably not sold because their finder thought they were worth more than buyers were willing to pay… To be brutally honest not many metal detector-found buttons are valuable, especially if they are in the usual soil-corrosion condition all my (south-east England) finds were.
But please don’t throw the buttons you find in the trash bucket or the hedge! Every button tells a story, even if it won’t line your pocket. To paraphrase what Joy Journeay, Treasurer of the World Button Association wrote, “Technological changes now allow us immediate access to old buttons and the rich history they share. Long after our clothing has disintegrated to dust, the buttons which held it remain . . . However a button was worn, it was handled hundreds if not thousands of times . . . Buttons hold our clothing: they also hold our history. Language is not needed to convey the button’s intimate role in our daily lives, whether lived in a hut or a salon of leisure.”
If you can’t find what you are looking for please contact me.