Ok, it's a slow day at work, and I love your blocks!
In case you don't have easy access to a fabric store, I added in a few sashings digitally. These might give you a rough idea of what you're looking for.
I like the darker colours more; I find the light/bright ones draw attention away from the blocks.
Light navy:
[ATTACH=CONFIG]546384[/ATTACH]
Medium blue, similar to the background of the blocks:
[ATTACH=CONFIG]546385[/ATTACH]
Dark green, close to the dark part of the leaves:
[ATTACH=CONFIG]546386[/ATTACH]
Medium green:
[ATTACH=CONFIG]546387[/ATTACH]
Dark yellow, similar to the dark parts of the flowers:
[ATTACH=CONFIG]546388[/ATTACH]
Light yellow: (almost white... actual white looked unnaturally bright because of the lighting in the photo)
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