preschool director here.
First be sure to follow the guidelines. many schools are peanut free and others have other health guildline.
After that, consider trying to match the snack to the weeky theme if there is one. It is so much fun and the children love it and teachers appreciate the reinforment.
Last week at our school was "B" Bear week. Throughout the school we had teddy grahams, banannas, blueberries, blue milk, blueberry muffins, blue pudding(vanilla with color), teddy shaped sandwiches to name a few. This week is ocean and one parent is sending in blue jello with gummy fish in.
If your school does not have themes, some stand-by favorites are:
fresh fruit
fun shaped crackers
cheese
drinkable yougurt
pudding cups
muffins
tiny sandwiches (do not add mustard/mayo etc.
Just plan and prepare with your child and have fun with whatever you choose.