I forgot about the roses and candygrams--that was when I was a little older, junior high (candygrams only) and high school (both). I don't recall ever having a bad experience with them or thinking they were awful. Usually people who were dating would get them for each other, especially the roses in high school. With candygrams you and your best friend might send them to each other. Not many people really got them overall, so it wasn't a case of, "Ha ha, Bobby's the only one in the room without any!" People talked a lot about sending one anonymously to someone they had a crush on, but it never really happened as far as I recall.
In both junior high and high school kids would arrange to have flowers or balloons delivered to their SO at school, too. The local florists would run a low-cost special with that audience in mind--for some reason, a single helium-filled mylar balloon attached to a can of pop to weight it down was the "in" thing. You could add a single rose if you were the classy sort. My personal favorite was the mylar balloon with a face on it and streamers for arms and legs, and pennies in the feet to weight it slightly--they would drift creepily through the halls like they were "walking" if you didn't keep an eye on them. The teachers were pretty good about keeping the distractions of the day to a minimum.
In all of these cases I didn't really notice people being sad or left out. Well, of course some people who had a silent crush on someone else would hope against hope that their crush would magically notice them, fall in love, and single them out with a huge bouquet of flowers in front of everyone else, but--that's pretty unrealistic no matter what. Usually these things were agreed upon in advance by people who were solidly dating, so although Katie's friends went "awww!" when Tommy sent her a rose, no one was really surprised. Guys who didn't send their girlfriends something might get a little ribbing on the day, but I never heard any drama about them that lasted longer.