On Fri, 19 Feb 2010 11:36:01 -0800 (PST), troyc
wrote:

Make sure you get clean straw (straw can be full of weeds & seeds),
and don't work it in to the soil - lay it on top. Straw worked in to
the soil will rob nitrogen for a time as it decays.

How about some bark chips? unlikely to include seeds.

J.