Start with the documented color character
Mushroom SW-9587 has a light-to-medium reflectance value; the name alone does not establish a precise undertone. A physical comparison is needed to decide how that character works with your own finishes. Mushroom SW-9587 is much lighter than Moth Wing, though its name alone cannot settle whether a room will read it as beige or taupe.
Travertine and undyed wool give a material-led way to assess the authentic sample without inventing an undertone from the screen chip.
Use Shiitake as a control
Use Mushroom and Shiitake to clarify the undertone choice against travertine and undyed wool. Keep the sample edges touching the fixed material, and cover one color before judging the other. Near-neutrals can look noticeably different side by side; the final choice still needs to work on its own. Record the specific relationship you prefer, such as a clearer trim outline or a quieter connection to the floor.
Mushroom has an LRV of 57; Sherwin-Williams Shiitake SW-9173 is 51. The difference is 6 points, with Mushroom returning more light under the reference measurement. Shiitake is a warm neutral with a stony gray character. This supplies a named color control; the LRV gap alone does not identify the warmer, greener or pinker paint.
The condition for keeping Mushroom
Compare the actual sample to the stone's background color before labeling it taupe, beige or gray in your scheme. The warm-versus-cool comparison covers that related choice.
If the unwanted cast remains beside a permanent finish under normal light, that is a practical reason to replace Mushroom. If it appears only beside an unused sample, remove the comparison and assess the intended palette alone. Before ordering samples, compare room-planning features in the paint color visualizer roundup.
Sources & notes
Color specifications: Sherwin-Williams Mushroom SW-9587. The recorded LRV is 57. Named comparison values come from the respective manufacturers; material schemes are editorial suggestions.
This guide reviews published color information and proposes practical sample checks. It does not claim first-hand paint testing or customer-review scores. Sherwin-Williams does not sponsor or endorse this site. Product names and trademarks belong to their respective owners. Confirm the color in a physical sample and select the coating for the actual surface and finish.