Australomisidia cruentata (previously Diaea cruentata).
Other Names: Blood-Stained Flower Spider, Crab spider, Australomisidia cruentata, Diaea cruentata, Diaea bilimbatus.
Family: Thomisidae (Crab Spiders). Over 120 species in 23 genera in Australa, many more are still undescribed. About 2,100 species in 175 genera worldwide.
Size: Male body 3 mm, female body 5 mm
Distribution: Common in NSW and QLD.
Habitat: They are especially common in flowers of Pultenaea species (which are bush peas with yellow flowers, sometimes called "Eggs and Bacon").
References: Whyte and Anderson.
Note that dead spiders usually fade in colour, so nearly all the spiders will look blacker or darker in colour in real life than they do in the photos of dead spiders from the museum.
Photo taken at Australian Museum, Sydney. High Resolution 2468 x 1712.