For my sons Kindergarden Valentine party I made Jello Jiggler hearts and put a sucker stick through each one with a Hershey Kiss on one end and a Starburst on the other end.
The marshmellow pops were a hit! Just place a marshmellow on the end of a sucker stick, dip in candy coating and add a M&M on the top. Add sprinkles for extra cuteness :)
The treat bags I used tall Cello bags and placed a store bought Valentine in the middle of each bag. We had a small candy buffet and the kids filled these bags with the candy from the buffet.