The 2 times I've remoisturized buds I used a small piece of banana peel in with the bag the buds were in for a day. The second time I used a few pieces of orange peels. Orange peels worked better of the two, but both worked.
A way I've never tried, but would probably work is take a jar and put your nugs in it, then fill a 2 liter bottle cap like half full of water. Then take the bottle cap and set it on top of your buds/middle of the jar. (rest the cap on top of the buds without spilling the water on the buds) then leave the jar in the hot sun for like 2 hours. If the jar was sealed air tight I'd imagine the water would fog up the jar and force moisture into the buds.
Get some good clean water on your hands, just barely wet, and flick the moisture droplets (not too much, if there's only 'a few buds') into or over the open container that they're in. Then re-seal it, and check it every so often. It will rehydrate. Even somewhat evenly over time, due to humidity seeking a balanced level.
everything mentioned works well, if you dont wantyour bud to pick up any extra flavors, i suggest a piece of lettuce in your nug jar, and check it everywhile because lettuce is very highin water, so molding could be a problem if your not to attentive.
I like to use a piece of damp kitchen sponge. I cut a 1/4" sliver off of one side and wedge it in the top of my jar. Just use a damp piece, NOT soaking wet. You can rehydrate too much, too easily. It works in a couple of hours. No flavor or smell is added like using fruit.