Nepeta is one option, I can see a likeness to many genera which are all in Lamiaceae. It might be necessary to see flowers to know for sure. The leaves are rounded on the tips, most leaves have a slight point.
Scutellaria has a trailing habit, Calamintha grandiflora has similar leaves and spreads by stolons. There's far too many species to go on leaves alone unless someone has it and recognises it.
http://erick.dronnet.free.fr/b...
Nepeta x faassenii has similar leaves..
http://www.lovelynx.co.uk/html...
http://en.wikipedia.org/wiki/F...
There's even a likeness to some Oreganos such as Mexican Oregano, Lippia graveolens, in Verbenaceae.
http://www.digthedirt.com/plan...
http://www.worldbotanical.com/...
Yes Myriam, Sanguisorba is similar, I can't find any with leaves quite like this though. I've seen similarities in so many plants!
