What is this mushroom? Its yellow underside tells us more than the cap

This is a bolete. The yellow underside with fine pores shows that it has tubes rather than gills, and the overall combination of a brown cap and yellow pore surface fits the slippery jack group best.

The photographs show a smooth to slightly matt brown cap, an evenly yellow underside with very small pores and a fairly stout stem. The habitat, with needles, stones and low vegetation, also fits boletes in late summer in Västernorrland, Sweden. However, not all details needed for reliable species identification are visible, such as a ring on the stem, how the cap feels in wet weather or whether the flesh changes colour when cut.

If you mainly want to know the type, ‘bolete’ is a useful answer, with slippery jack the closest match here. To go further next time, photograph directly beneath the cap, the full stem from the side and, ideally, a fresh cut through the mushroom just after picking.