Adding lots of compost to garden
Last year, my garden was brand new and we had some great yields. I went through and sifted rocks out of the soil, and it's not too terrible, but it's a little on the clay side and I'm sure it could be better. Our outdoor compost pile didn't amount to much, and our indoor vermicomposting bin is still relatively new so it won't be contributing a whole heck of a lot to the garden this spring.
I recently found out that a city about 30 miles from us has a community composting program (assuming mostly grass clippings and downed leaves, but I don't know for sure) and they offer free compost to anyone who can haul it away.
This year I'm starting a couple of raised beds in addition to my traditional garden and am planning on taking advantage of the free compost when it warms up a bit. Would it benefit me to get a truck load for my garden to till in, or should I hold out and pay for something like mushroom compost that I know its composition, more or less?
It makes sense to me that compost is good, regardless, but with how well we did last year I'm hesitant to put a whole lot of something into the entire garden because if it does more harm than good it's basically irreversible on a short time scale.