Is it going to be an indoor party?
I really love Martha's idea with the sparkling punch,you could also freeze lime green ice cubes (use lime juice, or just a tinytinytiny pit of green food coloring in the ice cube tray), because that's Tink's color. I know for a fact kids LOOOOVE sparkles, so you can try to put them anywhere just to add to the thrill (and it doesn't have to be messy). If price is an object, you could always make your own pinata with papier mache (it's not too difficult, but making a Tinkerbell shape may be...you might have to go with a star or something similar but simpler), or just take a light pink or light green tablecloth and glue sparkles all over that, and you can get those tablecloths for fifty cents. Do that same with sparkles on green and pink balloons, and get them filled with helium...you can also use and silver or sparkly Sharpie and write "Amelia Turns One!" on the balloons.
You can also maybe buy a smaller cake, and then make little cupcakes too, with green and pink icing and maybe a Tinkerbell decal, if you can find one...if not, you could just use cute little color coordinated sprinkles. For an easy activity, you could lay out coloring sheets of Tinkerbell, and the kids could do that for awhile.
Chocolate covered chopped up strawberries are a really cute idea, I say go for fruit and pastries mostly, but in small portions because the kids are little. And acruz suggested the silver serving platters, those are great and you won't have to worry about them breaking...remember, add sparkles to everything!
I'll keep brainstorming.