Place the yellow dandelion petals in a heat-safe bowl or jar.
Pour 4 cups boiling water over the petals.
Stir gently.
Cover the bowl.
Steep the petals for at least 4 hours.
For deeper color, steep overnight in the refrigerator.
Strain the liquid through a fine mesh sieve or cheesecloth.
Press gently, but do not mash the petals.
Measure 3 1/2 cups of dandelion tea.
If you are short, add a little water.
Pour 3 1/2 cups dandelion tea into a large pot.
Stir in 2 tablespoons bottled lemon juice.
Stir in 1 box powdered pectin.
Add 1/2 teaspoon butter if using it for foam control.
Bring the mixture to a full rolling boil over high heat.
Stir constantly so the pectin dissolves evenly.
Add 4 cups sugar all at once.
Stir well.
Return the mixture to a full rolling boil.
Boil hard for 1 full minute while stirring constantly.
Remove the pot from heat.
Skim foam if needed.
Ladle hot jelly into clean jars, leaving 1/4 inch headspace.
Wipe the rims.
Add the lids.
Refrigerate the jars or process them for shelf storage.