I poke around Pinterest some. A great place to get some inspiration... or a great place to get some laughs.
I stumbled across a pin that showed bleached pinecones...
We decided to follow the directions on the link and bleach up some too. They suggested soaking the pinecones for a few hours.
After 3 DAYS, the pinecones still weren't what Pinterest promised. More gray than white.
Oh well. Great lesson in "You can't believe everything you see on Pinterest."