Google on "soil amendments". Most places that sell it in bulk have a product especially for vegetable gardens that won't contain anything toxic. Here's one example of a company that does that. (link). There are many others. The delivery fee is always the most expensive part so if you can go get it yourself with your own truck you'll save big.

One other thing you can do is check with horse stables. They often have a pile of stuff you can take for free. Pile it up and cover it with a tarp for 6 to 10 months, and you've got wonderful amendment for next spring.

Here is a link that might be useful: one company that sells bulk amendment

Thanks. I did found site http://www.calrecycle.ca.gov, that list all bunch of the companies. And called one from the list, the one in Riverside, they told me they sell compost. When I got there, it was just a mulch, no compost.Very good mulch, but just a mulch. So that was rather annoying experience, especially since I had to drive more than hour to get there. That's why I asked question.
There are horses owners around us, actually, but only one does not treat her animals with steroids and antibiotics, and that one already gave away almost all manure.
I'll try one more company from that .gov site, and hopefully this time my one hour drive will not be in vain.

Mountains East of Los Angeles and zone 5?

OF Wolfinbarger in Chino sells a variety and would be my choice for a small quantity like a couple yards.

If you are not driving your own pickup then you are going to have to choose a very local nursery to deliver to you or the delivery price will be way too high. A long bed full size pickup will hold exactly two yards but you have to load it carefully to get it all in and tarp it securely after its loaded.

IME, 'compost' is going to be partially composted mulch from suppliers. What you need to ask for is humus or nitrohumus. That is the stuff that is completelycomposted.