It looks a bit like Lantana involucrata, which is somewhat poisonous, though I have heard that some people make an herbal tea out of some lantanas for coughs and colds.

I'm not sure though. Here's a link with pics.

Here is a link that might be useful: native lantana

I don't think it is oregano. I think it is Lantana.

The only way to tell if it is a lantana is by the smell, you cannot mistake that strong smell!

You maybe have mexican oregano, scroll down in the link where is says other herbs called oregano. I grew it in Arizona and it was big and bushy, I had it in a trellis. Little goes a long way, it does not taste like regular italian or greek oregano. If you use it, do it very sparingly in soups or chili or any other food that can take the strong flavor.
I hope that your herb is not a lantana...

Silvia

Here is a link that might be useful: mexican oregano

I didn't want to say it was a lantana, though it does resemble one. The leaves are just too deeply veined. While the leaves of a lantana are somewhat similarly veined, the leaves remain fairly smooth looking while the leaves in this image look... poofy. The lobes on the flowers look more defined than I am used to with my lantana blooms as well. But I didn't want to rule it out, keeping in mind that there could be other factors causing the leaves and flowers to look this way. But after looking up Silvia's Lippia graveolens, I think she might be on to something. This plant has very similar flowers and leaves to the one pictured complete with poofy-looking leaves and lobed flowers.

As Silvia said, get down at the plant's level and take a whiff. If it is a lantana, you should get fairly assaulted by a very earthy scent. A closer/better look at the 'berries' would help to differentiate the the two as well.

I don't think it's a Lantana.
I've got lots of the feral stuff growing along my fences where they can't be killed because enough of the plant is in the neighbours' yards! This plant definitely doesn't smell like Lantana.

The leaves on this plant are quite small, no longer than 1/2". For perspective, the orange cord in the picture is an extension cord and the black "cord" at the bottom of the photo is 1/4" irrigation micro-hose. I've seen it flower a couple of times now, but have never seen what the fruits look like.

Thanks

It does resemble white lantana, but leaves & flowers are slightly different.

Found this, 'Lippia graveolens' - flowers are similar, but the leaves look a bit different than yours...

Google image search can be a handy tool for stuff like this

Here is a link that might be useful: Mexican oregano