We saw collections of these mini stupas around Bhutan, generally at spiritual places.
Stupas are large structures built to represent Buddha’s holy mind. Building a stupa is seen as a way to purify your karma and gain white stones (positive points towards your balance for the decision of your next life). Some people can’t afford to build large structures so they provide small stupas and our guide called these ‘poor man stupas’. I love the way a bunch of them look, a community trying hard to increase good will.