Try putting the samples against a green or purple background -- those colors tend to make yellow "pop out".

Confirm your hunch by putting the samples against a yellow background -- a cool undertone would be more obvious against a yellow background.

Linen white?

BM Marscapone, I believe has yellow undertones.

We used a Glidden eco paint called Freshaire (?). The color is Distant Star in eggshell. It looks white on our walls- but the chip up against most other "whites" looks yellow. I love it- and it might be what you want. Got it at home Depot.

We tried a bunch of different whites when we repainted (our kitchen/LR/DR/entryway/hallway). To us, BM's Chantilly Lace appeared to have yellow undertones. Mascarpone might have as well--I know it wasn't a stark white (none of the Aura/Affinity colors are BTW).

(We wanted a white-white, so didn't use either color--used Super White)

Take a piece of bright white copy paper with you when picking out chips. Hold the whites against it and see what color hints they give off. There will be very little actual tint in a "white" color, so if the color looks great to you, get a sample and don't second guess yourself. "Yellow" can be created from a couple of different tints, such as yellow oxide, brown oxide, medium yellow, permanant yellow, so if you want to narrow it down to a more specific type of yellow undertone, then you're going to need to involve the paint mixer or maybe do a custom color.

Thanks for the info. I looked at my chips last night against both a white and a purple background. Although I liked a few of the colors mentioned above, I think I'm leaning toward paint chip 2151. It wasn't on my list above, but I like the vibe of the whole card. The lightest color is called Powder Sand, but Linen Sand is also nice. I'm going to have some samples mixed and see which one I like. I'm even considering mixing the two up as Powder Sand seems just a bit too light while Linen Sand just a bit to dark. Or maybe PS on the uppers and LS on the lowers. Hmmmmmm.

You can also have the paint store mix the Light Sand one (which you say is a bit dark) at less than 100% tint. At my BM store, they have a little sample card that shows the same paint mixed at 25%, 50%, 75% and 100% tint. If Light Sand had the right undertones, but is a wee bit dark, you could ask them to mix it at 80% -90% tint (or whatever percentage seems right).

acadia white

We use BM Ivory White #925 throughout our house. Very subtle creamy yellow - but still a white through and through. We went with it since it is a little warmer than White Dove.

Try Benjamin Moore Lambskin.

We went with acadia white in our house and I remember looking @ Mayonaise and decided against it because yet beautiful, too yellow for our trim. It may be perfect for you:)