Check your local parks and recreation department, roads or sanitation.
They may have free wood chips available. I get an unlimited supply
from my city. If you ad them every year you will build some nice,
loose soil and it will be very easy to pull the weeds in the future. I
add a little fresh fertilizer under the chips to compensate for that
nitrogen which is used while they are decomposing. Also, I haven't had
any problems spreading fresh grass clipping thinly over my garden. I
don't put them on any plants and they dry quickly.