A basic grass and some wild flowers, each with a particle system setup so they can be easily imported to your own scene.

Layer 1: Example set up
Layer 2: Grass models
Layer 3: Plantago Major (Greater Plantain) models
Layer 4: Sinapis Arvensis (Charlock) models

The more variations for each plant, the better the finished scene will look, so I've also included the base parts, blades, leafs flower heads, etc, on Layer 5 so you have the option of building up more variations easily if you want.

Greater plantain leaf texture from image by aauf:
https://www.flickr.com/photos/auff/15008403916/

Charlock leaf textures from image by Derek Lilly:
(The address contains an 'at' symbol, so blend swap will not allow it in the description)
https://www.flickr.com/photos/60892750 'at' N00/9100265866/
and Ferran Turmo Gort:
https://www.flickr.com/photos/fturmog/2384558569/

Charlock petal texture from image by Ferran Turmo Gort:
https://www.flickr.com/photos/fturmog/2385391088/