In Southeast Asia, sliced dried bael fruit (200 g., $3.49) is used to prepare a medicinal infusion; elsewhere it can also be found in ready-to-mix, sweetened form. Apart from spicy tamarind paste, Vientiane Grocery sells little in the way of prepared or homemade food and, if you discount the videos and knickknacks, apparently nothing imported from Laos.
I did observe packages of chewing tobacco, on open shelves rather than behind the counter, accompanied by lime paste. Also a frequent ingredient in paan, lime paste sensitizes the inside of the mouth and enhances the potency of the chaw, for good or ill.
Vientiane Grocery & Video
426 Chelmsford St. (near Factory St.), Lowell, Massachusetts
978-937-9399
(From a September 2011 visit)