When leaves are used as the toggle on a bracelet, they become the focal point and the band no longer vies for attention.
When grouped together (5 or 6) they make a nice pendant for a St. Petersburg chain. The one here is done in southwest colors with black accents.
Notice the black leaves on the pumpkin colored sweater. The leaves were don in black with red tips matching the colors in the sweater. Later the leaves were sewn on to cover a pull in the knitting and complimented the embroidered leaves in the green thread (not visible in this shot).
Hopefully, these examples have given you some inspiration.