[ RadSafe ] What fertilizer - specifically????

[Ted de Castro]

I need to give a general radiation talk and want to include samples of 
radiation around us ....

I have my Fiestaware, lamp mantel, sand from the beach in Kerala India, 
smoke detector sources, DU, NoSalt and thought maybe a small bag of 
fertilizer would go well.

Any specific suggestions to make my quest quicker - and yeah yeah I know 
- not in a crowded store with lots of customers and volume full up.

Thanks for your help.