@bonifartius @dude You can use whatever you want, it doesn't matter, just avoid too much pine tree wood, not because it's "acidic" that's an urban legend, but because sap is resinous and takes longer to decompose.
You also need to know that the caliber of the woodchips will influence heavily the micro biological life domination in the soil.
If you go under 1centimeter then the wood chips will promote bacterial domination, don't go too small like sawdust, sawdust won't be beneficial, it won't permit the soil to breath.
Bacterial domination makes you soil more Alkaline thus veggies will grow better in it.
And over 1 centimeter then the wood chips will promote fungi domination.
Fungi domination makes you soil more acid thus trees, fruits trees and bushes will grow better in it.
My big recommendation is to make borders between the grass and the mulch, the grass will invade it, sadly can't do my borders right now due to logistic issues.
Anyway here's a book on the subject of gardening I recommend reading.