My opinion is that something would be nice as a flower or a fashion item, but I think a wonderful gift would be something handmade as gesture counts, not the gift .
For my 30th birthday my family took me out to eat at a nice steakhouse. We also went to see a play. Sometimes giving someone a gift like this of an activity can be a nice replacement for "stuff" because the memories last a lifetime.
There are lots of t-shirts with the "over 30" theme, for example, "Over 30, so I can't trust myself anymore." A party with all black decorations would be fun.
30 chocolate kisses, 30 pennies, 30 anything the person likes wrapped in 30 pages of newspaper...! "Consumables" are always great gifts, anything they'll use: specialty foods, car wash coupons, etc.
