To build a guild think soil, roots, and results. A mature ecosystem has a rich layer of biomass that has accumulated over many, many years. In order to replicate, create your own layer of rich topsoil using a good combination of nitrogen and carbon rich materials. Hay, fresh manure, and grass clippings work well for the nitrogen layers and straw, newspaper or carboard, and compost work well for the carbon layer.
Start by cutting the grass. Leave the clippings to mulch in place and cover these with a thin layer of newsprint. Atop the newsprint, pile four inches of fresh(ish) manure. I pile the hay (not straw) directly over the manure in another thick eight-inch to a foot layer and then cover these with a thicker-than-before layer of newsprint. Straw works well over the top to seal in moisture. The creates a weed barrier and holds in moisture and allows time for your grass-suppressing bulbs to get rooted before the paper biodegrades.
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