Photos follow to help focus this discussion:
This fall I've gone back to my younger years and picked a large quantity of Goldenrod galls / grubs. Searching the internet there few good articles on their collection, opening, storing, and use. Fallow farm fields and road and railroad ditch lines yielded most of my harvest. I found that picking the galls before mid-October was a challenge as the stems are green and woody and the galls are often hidden by plant leaves. Ideal picking was the last two weeks of October when stems are dry and much of the plants leaves have fallen. By November 1st birds had pecked out many of the biggest galls. Speaking of size, I found that it does NOT pay to pick galls the size of a dime or smaller as grubs very seldom exist in them. "Smaller then a dime - Leave them behind" Pick only larger ROUND and DARK BROWN galls. Elliptical shaped / non-round or any gall other then dark brown color are almost always empty, so don't waste the effort on them.
Storing galls in 5 gallon buckets was a mistake as they mildewed and got somewhat moldy. Best storage was in paper grocery sacks and burlap bags and they could dry out better.
Opening Galls: Various suggestions are out there about how best to open the galls to get the large BB sized grubs. I found resting ea. gall on a 2X4 plank and striking a hammer on a old kitchen knife was as fast and effective as any. See photo. Any way you open them, you are going to cut or squish several.
I estimate the success rate of getting a usable grub from a gall is about 1 in 4, taking into account those that you damage, empty galls or small sized grubs.
Time Saver: It is easy and quickest to cut open the galls and IF the grub is NOT immediately coming out, place opened galls in a cardboard tray or similar and place at room temperature for a few days and the grubs will crawl themselves out of the opened gall for easy harvest (see photo).
Storing grubs: You may know as I recalled, and I have now again experimented with, putting the grubs in ground cornmeal, then put them in a bait container in fridge or freezer. Bottom line is you can repeatedly freeze and thaw goldenrod grubs from fridge to freezer and back again without harming them. Its reported that the grubs have glycol-like body fluids that allow them to survive these changing conditions. I try and fish FROZEN grubs as they thread and hold better on a jig hook. Its NOT without time and effort. A paper grocery bag of galls = 1 and 1/2 times a 5 gallon pail) and takes 2-3 hours to pick in the field and another 5 hours to open them. All the while anticipation builds for the fishing fun to come with self harvested bait.
Welcome your goldenrod grub experiences.