Don't know if these are the exact shades you want, but three popular SW muted yellows (don't scream "sunshine") are Jersey Cream, Ivoire and Butter Up. You could take and look at them and see.

SW Ivoire

Room's a work in progress.

There's a bit of red in the formula which mutes it.

My cabinets are SW Ivoire. Depending on the light and time of day it is a variation of a creamy yellow. Idon't really think of it as a mustard yellow at all, but depending on what colors you put with it maybe it could go a little more that way. I also have a room painted SW Blonde that is the next color down on the paint strip that definitely has more of a mustard-yellow look.

Here is a link that might be useful: wicked grace ivoire cabinets

If you go to this link in Home Dec, you'll see I asked trailrunner to post her laundry area for you. A color called Belgian Waffle that I kept going back to, didn't go with, and after seeing on her walls wish I had.

If you hop over to the Home Dec Gallery, in favorite Yellows/golds thread, scroll down and you'll see SW Jersey Cream in my unfinished at that time family room. Within the first year it morphed a bit, the yellow toned down a tad and tan undertone amped up a tad. Like it even better now. (Note my room is very low light, use mirrors to bounce light around. J-Cream in a very high light room can tend to wash out.)