so my goal for this year was to remove the front lawn and replace it w/ a edible yarden. so far i've removed all the grass from the yard and excavated about 12" of top layer of soil. over the past 2 months i've been collecting fallen leaves from my neighborhood yards, getting wood shavings from wood workers, horse manure & picked up 13 bales of straw for free. i made what i think is a monumental mistake. i placed the leaves & straw directly on top of the excavated dirt. well, i noticed in one of my barrels with the collected leaves there was crabgrass pieces and it was forming new roots. not only that.. the straw had wheat seeds that are sprouting.. that stuff is impossible to get rid of when it takes root in the soil. should i remove everything i've collected and put it into a composting pile hoping the heat will kill the roots? there is just too much to sift through to find every little root.. i'm very beat down from finding these roots...
The reason why I think using other plants to deal with the grass is that some plants can be more polite with their behavior, politely bowing out when their job is done. A cover crop may like peas or legumes could grow and outcompete the grasses for a while, and they are at it, they will be fixing nitrogen in your soil. As for stuff like pumpkins, they would protect the soil from the sun's desiccating rays (saving the soil microbes) and provide a harvest at the end of it. Then, when you're ready, whatever was outcompeting the grass can be removed to make way for the actual yarden understory.
Don't worry too much . You do not need to take everything back out. Get some of your material composting well, you want to get all the microorganisms going strong and the composting process aids greatly in doing that. Then when you have some good compost made up, make some compost extract (like compost tea but without the aeration and growing time), and use the extract to water the area. This will introduce loads of the beneficial microorganisms all around the yard.
Getting a fungal dominated soil food web will work against the grasses and support more desirable plants.
Dr. Elaine Ingham explains it all wonderfully in a series of lectures on Youtube "Common Ground".