I think you would probably want to just stick to marigold flowers and leve the leaves to do their stuff..not because they toxic but because they don't produce a lot of green.
nasturtiums...everything can be fed..the leaves are lovely and peppery and you can pickle the seeds like capers.
Other flowers are violets/panseys, roses, lavender (if you bun is not expecting). YOu could also give them strawberry, rapberry and black current leaves.