Suillus quiescens is a pored mushroom of the genus Suillus in the family Suillaceae. First collected in 2002 on Santa Cruz Island off the coast of California, in association with Bishop Pine, the species was scientifically described and named in 2010. In addition to its distribution in coastal California, it was also found forming ectomycorrhizae with the roots of pine seedlings in the eastern Sierra Nevada, coastal Oregon, and the southern Cascade Mountains. It resembles Suillus brevipes, but can be distinguished from that species by its paler-colored immature cap and by the tiny colored glands on the stipe that darken with age.

Suillus is a genus of basidiomycete fungi in the family Suillaceae and order Boletales. Species in the genus are associated with trees in the pine family (Pinaceae), and are mostly distributed in temperate locations in the Northern Hemisphere, although some species have been introduced to the Southern Hemisphere.