Here is one of my favorite activities for the first day of school. (It even leads to a cute bulletin board!):
First I read aloud The Kissing Hand. Then we discuss the book and how each of us felt about coming to school today. I take quick notes as to what each child says. (I use the prompt "I felt ______" to get them started if they need help.) Then during station time, I have each child create two handprints. (I use those great large round ink pads from Lakeshore. So easy!!!) One handprint is used for a bulletin board display and the other becomes a puzzle.
Bulletin board: I make the bulletin board display after school by typing up each each child's response to how they felt on the first day of school. (Example: Diana felt excited because she was coming to school!) Then I post each child's handprint and typed response on a bulletin board. I post the handprints in the shape on a heart. (Hard to tell in the photo because I used a font that was too big last year.) If I remember, I even place a heart sticker on each handprint or on the typed response. Sometimes I like this board so much that I leave it up all year! (It is so fun for the children to look back on later in the year and laugh about how scared they felt on the first day.)
Hand Puzzle: During lunch, I quickly cut each handprint into about six pieces. It goes home on the first day in an envelope with a poem on front that tells parents to sit with their favorite first grade child and put together the puzzle inside the envelope. I love that it becomes a handprint that parents get to keep as a reminder of their first day of first grade! To make this easier for me, I have the envelopes prepped ahead of time labeled with the child's name and with the poem already glued on. That way I only have to cut out the handprints and put them in the correct envelopes at lunch. I cannot post the poem because I didn't write it myself, but found it on someone else's site (and I can't remember whose site it was. Sorry!)