I think the last photo is your strongest. I'm not a fan of the on camera flash so the first ones to me don't look like they're harnessing the power of your camera. The last shot though is well composed, well lit and all of the leaves contrast nicely with the background lighting. Couple of drawbacks to that photo are that the leaves are dusty, the soil spots on the inside distract the eye, and there is a spider web connecting a couple of them. I think it's a really beautiful shot though. If you use natural lighting as well as you did in the last photo with the first few, you'd have some really great shots. Keep it up!