I changed natural spell once along time ago;


Natural Spell [Metamagic]
Benefit: You can complete the verbal and somatic components of spells while polymorphed. You substitute various noises and gestures for the normal verbal and somatic components of a spell.
You can also use any material component or focuses you possess, even if such items are melded within your current form. This feat does not permit the use of magic items while you are in a form that could not ordinarily use them, and you do not gain the ability to speak while polymorphed unless that form is normally capable of speech. A natural spell uses up a spell slot two levels higher than the spell's actual level.

Keep in mind we home brewed druids so that they didn't get wild shape at all, but could opt to either spontaneously convert spells into either summon animals 1-9, poly-morphing/wild shapes, cures 1-9 or inflicts 1-9. Also druids who picked the Wild Shape spell casting tree got natural spell as a bonus feat at level 5.