As for the 'yellow' my sister is planning on using, she mentioned asiatic lilies as her basis for this particular color. So, I looked them up and here is a few pictures:

(www.ftd.com/.../f496/)

(picasaweb.google.com/.../7L5iqR7xVMA4NMGKeH_9SA)

Thus, I am trying to look for flower arrangements using her three colors.

(http://www.ncbuy.com/flowers/1_10457_asiatic_lily.html), (http://shop.flowershopsouthampton.co.uk/yellow--green-flower-arrangement-44-p.asp)

(www.flowerstodelhi.com/flowers4.htm)

(http://www.fiftyflowers.com/search.php?search_val=solidago)

Is this kind of what you are looking for, Jane?