I sort of like the Russian way where the flowers actually come from the fans. Of course, there are pros and cons to both ways of doing it.
I know that in some companies, dancers have sent each other flowers, for various accomplishments. I thought that was particularly sweet.
(I originally thought you were just referring to tossing flowers over the pit at the end of the performance, which has the added possibility of a tulip on the head...)
I think at the Mariinsky you are supposed to give the flowers to an usher or the backstage area (drop off) and tell them (or have a card) who is to receive it.
I don't think it is allowed to bring the flowers into the auditorium and toss them at the Mariinsky. Maybe it was allowed at one time, but I don't think it usually happens now, but I could be wrong. Rules are meant to be broken! LOL
I have seen in the U.S. people going up to the stage and handing or tossing flowers or torn up programs (for confetti), so I am sure tulips or roses can land on heads! LOL I read that Maria Callas once picked up radishes some disgruntled fan threw up onto the stage, and she sniffed them and threw them into the pit. She was near sighted so thought they were roses at first without her glasses (which she wore off-stage), but she was always quick to deal with anything that came her way, it seems.
I also witnessed first hand a young fan give Kathleen Battle flowers, and she refused to take them until he removed the plastic around them. In fact, if I remember correctly, she made a big show telling him and showing him to remove the plastic before she finally accepted them with a smile. I felt sorry for that particular fan standing there while she taught him etiquette while using bad etiquette (correcting someone publicly).
I would think receiving flowers from actual fans would be more meaningful to a ballerina than flowers purchased and given by the company. But I don't think I would complain where I got them either!!! LOL