Flower was the first single release from Soundgarden's Ultramega OK album. Like most CD singles, the real value is in the b-side. Both Flower and Head Injury can be found on Ultramega OK, but Toy Box is exclusive to this single. It's a really great song, slow, plodding and doomy in a Black Sabbath kind of way. It's well beyond b-side quality, but I can see how it wouldn't have fit with Ultramega OK's overall sound.
Flower is really only for die-hard Soundgarden fans who really want to have all of the band's recordings, and considering the fact that you can buy a download of Toy Box here for less than a buck, it's hard to recommend buying this expensive CD single.