As far as shopping for pillows and rugs, my shopping vlogs and I can attest — Home Goods is always a great option! Their pillow section has never let me down, and you can mix and match, just like Morven said!
To make the corner have a cozy, well-lit vibe, what about hanging a pendant light? This DIY Hanging Flower Light Fixture is perfect for a bohemian theme, and brings such ethereal whimsy into the mix! Almost like a Free People store!