Marcella of Power Poppy used to design for Flourishes. She does have a fantastic but unique (IMHO) style so I dont know how close we can get. I love that she often uses uncommon flowers for stamps-I am always very drawn to that kind of thing.
Are you looking for mixed flowers like hers or just fun to color?
You might like the new background stamps out of MFT...lovely and selling like hot cakes.
Technique Tuesday, the Mondo flowers out of Ellen Hutson...it is true. Flowers are one of the biggest categories so everybody has got 'em.
One way I might look is with large gen distributors like Ellen, Scrapbook.com, 1-2-3 Stitch, Frantic Stamper...Frantic and Topflight both have a lot of European stuff and are stateside...just ask for flowers and see what pops up. You may get a feel for particular mfgs you like