There is a strip of rotting wood between the concrete slabs on my driveway.
It is about 1" wide. Is this a standard lumber item, or would I have to cut
it from something else? Is there anything better than a strip of wood?

Between the driveway and walkway, and between the walkway slabs, there are
half-inch gaps but no wood strips in them. I don't know what is supposed to
be in these gaps, but now they are filled with random junk/dirt and topped
with moss. What is the proper way to stuff these gaps?