Rachel has little information about the badge - so if anyone can shed any light on it - I'd be happy for you to leave a comment!
UPDATE - 6th April, 2012
Ceri Garner-Jones who has kindly sent me some badges for recent posts also has this badge and says: "Any chance Rachel went to Dan-yr-Ogof caves or a dinosaur exhibition at the museum in Cardiff back in the 80s? Am sure it came from one of these! How very odd we both have this mysterious badge :)"
This actually jogged Rach's memory as she went to both Dan-Yr-Ogof and The Museum. I've tweeted both for confirmation so stay tuned!
FURTHER UPDATE - 31 May, 2012
I have since had it confirmed by Dan-Yr-Ogof that this certainly wasn't one of their badges which means it most likely originated from Cardiff Museum.