I would be looking for spruce and pine needles. That's what I'm using on my year old blueberries and raspberries. I'll be making a compost from pine needles for my berry patches. I'm not expecting them to completely break down in a year, but I do expect them to gradually acidify the soil.

You might try doing a hurry-up compost with oak leaves, pine needles and something like alfalfa pellets. Make a tea, bokashi solution from ground up oak leaves, pine needles and some sort of 'green', and spray that on the compost to supercharge its activity. Hot stuff.

And if you have fall leaves in your yard, use your lawn mower to crush them and use them as well.

I did save a lot of pine needles from Christmas -- I was planning to put that on top as mulch.
I don't have any leaves left, but I do have one bale of hay saved (my precious).
How about coffee grounds -- would that be quick too? I can get those at Starbucks.

see our straw bale raised garden bed, you could be planting into it straight away on completion.

len

Here is a link that might be useful: lens garden page