Or tonka beans, or tonkin beans... There are various different ways of spelling the word but these are the beasties and yes, they do look a bit like legless blackclocks (that's cockroaches to the rest of the world). Dipteryx odorata is the Latin name.
In the past they have often been used to keep snuff moist and also to impart that flavouring. They still do that job well of course. Simply dunk a couple in water overnight and the next day just pop them into your snuff, after dabbing off any excess of water. Rehydration and flavouring all in one go though it does take a couple of days for the best effect.
Recently I tried a little experiment, having ordered a 25g vacuum sealed tin of J&H Wilson's Top Mill No. 1 and having been sent a punch of the little blue tins, which inevitably contained rather dried out snuff. Disappointing, yes, but not an irretrievable situation. I had a go at revitalising some of the snuff with the water soaked tonquin beans and then thought why not use some other liquid? So, a day later, a couple of beans soaked in whisky and a couple in brandy and the now plump and juicy beans were added to two more lots of the Top Mill. Result? Delicious! We'll see what Snuff Head thinks about the result in the pub tonight.
Sources for tonquin beans? Snuff Store has them in stock sometimes. Otherwise I'm sure a Google search will reveal many more sources.