Great ideas - I'm surprised that petals have enough pectin in to set. Might give it a try, at some point, though I was planning to try rose petal wine this year (having finally got enough fragrant roses for a surplus of petals).

Don't forget elderflower too. Elderflower wine is very easy to make and very nice.

I have a recipe if anyone is interested ( off the top of my head:
1 pint elder flowers, with as much green removed as possible;
juice of 1 lime and 1 orange
knob of root ginger, scored
3lbs of sugar

Place elderflowers in pan with juice of lime and a knob of ginger, and cover with boiling water to sterilise. Leave to infuse for 24-48 hours. Then strain, and add 3 lb sugar, previously boiled with a small amount of water to make a syrup. When cool, add everything to a demijohn with the yeast. I use Sauternes/desert wine yeast.