Q.Do Goosegrass Seeds Contain Caffeine
YOur article on goosegrass describes the seeds as non caffeinated coffee substitute, but other sources which I consider reliable note that goosegrass is related to coffee and that the seeds contain caffeine (hence their use as coffee substitute – preferably with dandelion for the flavour which goose grass doesn’t provide – it just gives caffeine)

Certified GKH Gardening Expert
No, these do not contain caffeine as part of its chemical constituency. They are related, but at the family level. They are quite far apart in their genera, and will not bear much resemblance. This piece from the Wisconsin Horticulture Division of Extension will offer some more information on the plant:
https://hort.extension.wisc.edu/articles/catchweed-bedstraw-galium-aparine/