Identification help for green bases
Those are Sports Field Sections 8 x 16

https://www.bricklink.com/v2/catalog/catalogitem.page?P=30489

https://www.bricklink.com/v2/catalog/catalogitem.page?P=41819c02

They appear in soccer sets



The sets are playable, you can move minifigs on springs to "shoot" the ball, or defend with the goal keeper minifig...