What does "有蛋黄的迎春花" mean?
迎春（学名：Jasminum nudiflorum），又称金腰带，香港俗称串串金，是木犀科素馨属的植物。早春先于叶子开放出黄色鲜艳的小花(bright yellow flowers)，给人们带来春意，所以花名曰迎春。

Winter jasmine (Jasminum nudiflorum) is a slender, deciduous shrub native to China. It is widely cultivated as an ornamental and is reportedly naturalized in France and in scattered locations in the United States.



Let's inspect the structure of the phrases.

蛋黄的迎春花
粉红的桃花
白色的玉兰花
紫色的丁香花  

These are appositives.
They have the same pattern, color + flower name.

The author uses two words (+ 的) to describe a color.
Thus, 蛋黄色 is simplified to 蛋黄, and 粉红色 to 粉红.

蛋黄(色)的花 egg yellow flowers