Lysimachia nummularia ‘Aurea’ (Golden creeping Jenny, Moneywort). This is sold as an annual for pots and hanging baskets, but it's a hardy perennial in my garden surviving snow and frost happily. I have planted it as ground cover and it snakes it's way beautifully around other plants providing a shock of bright lime green contrast.
Creeping Jenny (Lysimachia nummularia "aurea")
Creeping Jenny, Moneywart / Full sun to Part Shade / For containers / Ground cover / Spread over 30 ft.