Help! Dessert Buffet quantities needed

I'm doing a dessert buffet for a local garden club. they will be expected to register, take a dessert or more(hence it's a buffet) grab a tea or cofffee, find a seat, visit then the meeting will begin. I've never done anything where there was no dinner/lunch involved. So my question is how much should i prepare and how much of a selection would be appropriate? there will be 230people in attendance. also any creative dessert ideas? I was thinking since it is a garden club to use a floral/herbal theme.So far i've thought of:
Proffiterols with Thyme infused pastry cream with a honey caramel sauce, individual French lemon tarts with violas, Blueberry lavender cheesecake, Spiced chocolate tart & Carrot cake. any thoughts?

great idea, i was also thinking a heaping pedistal plate of Macarons

I totally agree about the consumption, i'll learn more this aft, going for my consultation soon. love your ideas Shroomgirl , can'yt do lemon verbena or Greranium ( did think of those actually)but my lemon verbena won't have grown enough by then and we can't get sented geraniums in cause our climate is only a 2b-3a area( i'm really disapointed!), i did think of cupcakes but there are a lot of men too so i thought a littke too feminin.lokked the wheat grass idea though hadn't even gotten that far about the table yet.& the rosemary lemonaid is Fab! but i'm not incharge of drinks,i think, will know more this aft. So you think 600-700pcs is needed? i was thinking people would probably take an average of 3 pcs.the plan is: they are to take, visit a little bit while others register then the meeting starts, there is no getting up cause i was suggesting my choc. fountain(would've been very easy!) but it was nixed cause no one wanted people getting up with the guest speaker talking. so 3pcs x 230ppl=690pcs it's on a monday in the evening around 7pm( just from memory of them in the community)so i guess i was on the right track since you suggested 600-700pcs.And your right Ed, it is more labour intensive so these ideas would suppliment more easier cakes & tarts that would also be different but a little more traditional. I'm going for a genaeral theme of unique herbal but those would be sprinkled among easier desserts that would also be delicious. i';m figuring they would balance each other out on the labour end. Last question is how much variety should I have? i was thinking 8?

The garden club executive was floored, very excited. and yes based on their last years figures 3.5 pcs/pp for an average in servings. thank you all who helped, Shroomgirl your ideas were fantastic & Ed, thanks so much for the practical side ( not my strongest area, as my husband kindly reminds me).
TrulyS