I cannot browse the live Xbox 360 Marketplace (store largely deprecated, purchase disabled July 2024). However, here is how to search:
site:xbox.com "Yin Yang" gamerpic or "Yin Yang" "Xbox 360" "gamer picture".marketplace.xbox.com may show old gamerpic packs.Generic "Yin Yang" symbols were common in free gamerpic packs (e.g., "Symbols Pack," "Chinese New Year"). If it was a limited-time promo (e.g., Kung Fu Panda tie-in), it may be unobtainable now.
Modern Alternative: On Xbox One/Series, you can upload a **custom image** (via Xbox App → Profile → Custom Gamerpic) of any Yin Yang art you own.