If so, you've seen the noxious weed called Common Tansy (Tanacetum vulgare).
This plant is listed as a noxious weed under the Alberta Weed Control Act because it contains alkaloids that are toxic to livestock and humans. According to Montana State University there have been cited instances of cattle becoming sick and aborting due to ingesting Common Tansy.
These plants have dense creeping rhizomes that primarily grow in the top two feet of soil where they gather as much water and nutrients as possible, making it highly competitive and a threat to biodiversity.
If you are going to remove these golden buttons from your landscape, try to remove as much of the rhizomes as possible—remember to wear gloves and other protective clothing to prevent absorbing the toxins through your skin.
While mowing this weed keep the blades at a high setting to reduce seed spread while leaving desirable plants in the understory unharmed.
For more information about Common Tansy, check out this fact sheet.