Here is a nature-inspired color palette with a focus on sage green and various contrasting colors:

 <Nature's Harmony>
1. Sage Green - 
          
          #B2C8B2
        - A soft, muted green that embodies the essence of nature.
2. Earthy Brown - 
          
          #8B5B29
        - A rich brown reminiscent of fertile soil.
3. Sky Blue - 
          
          #87CEEB
        - A light, airy blue that reflects clear skies.
4. Golden Yellow - 
          
          #FFD700
        - A vibrant yellow that captures the warmth of sunlight.
5. Terracotta - 
          
          #D56E3D
        - A warm, earthy orange that evokes the feeling of natural clay.
6. Deep Forest Green - 
          
          #2E4A2E
        - A dark green that symbolizes the depths of a forest.
7. Lavender - 
          
          #E6E6FA
        - A soft purple that adds a gentle contrast and floral touch.
8. Coral Pink - 
          
          #FF6F61
        - A vibrant pink that brings energy and warmth.
9. Slate Grey - 
          
          #708090
        - A cool grey that balances the palette with a neutral tone.
10. Ocean Teal - 
          
          #007B7F
        - A deep teal that reflects the beauty of ocean waters.
11. Wheat Beige - 
          
          #F5DEB3
        - A warm beige that adds a light, sandy touch.
12. Berry Purple - 
          
          #6A0DAD
        - A rich, bold purple that adds a striking contrast.

This palette combines various nature-inspired colors, including the desired sage green, to create a harmonious yet vibrant selection suitable for Excel. The contrasting colors help to emphasize different elements while maintaining a natural feel.

Would you like any specific colors adjusted or additional colors added? Or do you need suggestions on how to use this palette effectively?