These are the supplies that I used, feel free to use whatever you like. 

Watercolor paper, mine is 11x11 (You could also used mixed media paper)

Something to make a large circle on your page, I used a glass bowl

Fine black pen, I like Pentel's RSVP

White gel pen, I like Signo Unibal

Pencil and eraser, I always reccomend either a black or white eraser, they erase clean

Watercolors:

Straw color, I used yellow ochre

Light and dark green that you like together for leaves

Light and dark purple that you like together for flowers

Watercolor bruhes:

I used an 0, 4 and 6 (I think, the numbers are worn off two of them!)

Again, don't get too hung up on the exact supplies, use what you have/want, it'll be fine. We're just having some fun here :)