You could draw from the colors in the pillow and use a lighter or a darker version of the yellow or green. I wouldn't suggest the blue because that might blend in too much with the couch unless it was much darker or a different shade.

Guilford Green HC-116! Or in the ballpark.

How about the background (taupe) color of the pillow? Then use accents of the yellow and / or blue?

I agree with Karen, use the grey(taupe) of the pillow's background.

Oh I think a fresh but warm white would be lovely...try, BM white dove, if you want more depth try Revere pewter

Sherwin Williams accessible beige- shows up as a light grey.

Restoration hardware cloud / or buy their pinwheel for a few bucks and hold it up to your couch. I love that they only have a few great colors to pick from so it's not such a dizzying choice. Home Depot or other stores can color match.

Work with the color of the sofa. I have that same fabric in a pillow and it goes with so much. I have it with Browns and blues. You don't want sofa to disappear against the walls. So either a color lighter than the sofa or darker.

A pale yellow would look great against the couch and bring out the highlights in the throw pillows. Perhaps something like Benjamin Moore's Copacabana

Here's an example:

BM Bleeker beige or Manchester Tan for a slightly more grey hue.

Manchester tan actually has a more yellow undertone, not grey

Excuse me, if i may interject. The issue with colour is that everyone sees it uniquely, so when picking a paint choice it is best to see it in the light of the room, day and night and with interior lighting on in the evening. I would paint a portion of wall with an individual sample each day to see the difference. Take the time to play with the colour and eliminate as you go. My choice would be the lighter neutral colour that is bordering the flowers.

I agree with this previous comment- everyone sees color rather subjectively:) I live in army housing, so no offense, but any talk of white or beige or off white makes me want to puke:) haha-not really:) I say embrace the color! And yes, paint a large area and live with it through all sorts of lighting. Yellow is a wonderful clor, but it needs some serious reigning in so that you don't feel like you are living in a lemon. And that teal would be lovely, or a celadon type green. I think that copacabana another writer put up is so cheerful- but again, I would paint a chunk of the wall and visit it at different times of the day...have fun - don't panic:)