I created conversation heart bags out of felt, very similar to the ones created by Simply Feather. The difference being that I was too cheap to buy red fabric paint so I embroidered the messages. This worked for me because I only had 5 bags to create...but I would not suggest it if you are making a large number!
I stuffed the bags with various goodies: heart magnets inspired by Heidi Kenney, I used foam hearts instead of wooden ones (not the best choice) but my town is lacking in craft essentials. I picked chocolate instead of candy because there are some younger children at the daycare (no choking!). Finally, the typical drug store Valentine cards. Ethan picked Transformers for the boys and I convinced him to give the girls beautiful vintage inspired Valentine's that I picked up last year.