I'm a preschool teacher who does the 100th day thing, too. The whole point of counting to the 100th day is to expose children to larger numbers and the patterns that are part of counting to 100. They also get exposed to place value.
For the homework, your daughter should be doing the counting (with your supervision/assistance). There is really no point at all in having a mom count out 100 things to send to school; unfortunately, that is a lot of what I got this year.
Anyway, here are some ideas: 100 straws, toothpicks, stickers on a page, fingerprints on a page, rubber bands, buttons, pebbles, candies (glued to a page in the shape of a picture), etc. One year a girl and her grandma made a pillow with 10 rows of 10 buttons sewn on; it was so cool.