The Nether Core
If you mean Glowstone Dust, you get it from breaking blocks of Glowstone, found in the Nether.
You are not able to craft a blue flower in minecraft for the pc/xbox without the use of a mod that has a blue flower in it. There is only a red flower (Rose) and a yellow flower (Dandelion). Blue flowers (Cyan) are not planned to be put in pc/xbox game (jebtweet:78539168938078208) On minecraft pocket edition (pe for short) there is a replacement for Roses called Cyan (the blue flower you are talking about). They replaced the rose because of hardware problems (jebtweet:78539168938078208) Although the rose has been replaced there is still a dandelion in the pocket edition.
A yellow pocket is the corner pocket on a snooker table which is nearest to the yellow spot.
Sulpher / Sulfer (S)
Sulfur powder is typically bright yellow in color.
http://www.cuisinecuisine.com/BasicIndianSpices.htm find it here
A hole.
The yellow color is from sodium radiation.
You can substitute turmeric, cumin, coriander, and ginger in equal parts for yellow curry powder in your recipe.
Powder yellow symbolizes happiness, positivity, energy, and optimism. It is a bright and cheerful color often associated with warmth and sunshine.
Lycopodium
solid, yellow powder