Quite the collection!

I made the kids do some much-needed cleaning out yesterday.  While helping my 7 year old daughter tackle the space under her bed, 

we found this shoebox she'd covered in construction paper and stickers:

I opened it and the look on my face must have reflected my question because my daughter immediately informed me, "That's my cotton ball collection!"

Of course it is!

Because really everyone needs a "cotton ball" (pom-pom) collection!

So, tell me, what strange things do your kids collect?