
One thing I noticed was that a similar "flower-like" symbol adorns the center of an Aeducan's startup shield:

So Cadash's symbol has only four circles around its center while the Aeducan one has eight. Aeducan just adds an extra set of four. Thus it becomes immediately, completely, and unmistakably obvious that the round shapes of the symbol are not flower petals. Proven... isn't it? Ha! However, they're also nothing like the usual straight lines in DA dwarf art. Even seeming curves usually end up just being diagonal- but decisively straight- lines or blocks.

The entire elaborate dwarven throne room is made up of straight lines. Even the beard of the iconic hammer-wielding dwarf has no rounded curves or arcs:

I used to have pics of all the bas relief artwork in Orzammar as well- might have had round heads on the block figures, not sure, but otherwise just as straight-lined. Here at Alimar's Emporium you can see the straight grid ceiling and also a few of the bas relief artwork to the right. Completely ignore the vase to the left because it doesn't count at all whatsoever to these deliberations...

The same dwarfy style shows up in Inquisition too, of course, like this door down in Descent- still no rounded lines, just wear.

I don't have screenies from DA2's PT, but anyway, you get the idea- curves are rare. So considering the Cadash Stompers symbol to be dwarven might be a stretch... However, roundness does show up in dwarven art in two ways, both very dwarfy in origin: gems (as you can see in the above pictures) and stones...

So the round circles of the Cadash symbol could refer to gems or stones placed together in a pattern rather than some mere silly flower... Pfft...
Then I decided to pay more attention to the pattern itself: four similar/equal shapes with a different-sized shape inside. Suddenly a number of instances came up- plenty and prominent enough that at the very least, however easy it may seem to dismiss as Cadash's symbol otherwise, the pattern itself is a repeated theme in dwarven art.
One example I found was in a DN's starting armor. There are potentially two instances of it on that armor alone...


OK, the second instance above is a bit of a stretch, but there are four rectangles surrounding the belt's central buckle. I tried to avoid requiring any serious stretching of one's perception to make these pattern identifications more believable recognizable. Like on the Sha-Brytol armor's central buckle- yet again the pattern, albeit a tad less symmetrical... What? They have their own ancient heraldry...

Another instance was a pattern in the stonework around Jarvia's Dust Town hideout entrance. It's repeated three more times in mirror fashion around the door frame.

And that same Dust Town stonework pattern was also around a door in Kal-Hirol, though only one instance on each side:

It's even discernible in these tree-like lava-splash-like or lyrium-branches-like decor thingies about Orzammar's grounds (and the Shaperate):

If you look closely it has four equal branches all around a center point, but you wouldn't see it unless you were looking straight down on it.
OK, so most of the time the pattern shows up diagonally rather than having a single gem/stone/gemstone for top and bottom, left and right, as does the Cadash-wannabe symbol...
vs. 
But it's still a similar pattern! And it shows up curiously enough- and boldly enough- in the dwarven banner pattern at Skyhold itself:

And also in the pattern of lyrium at the top of the Kal-Shirok shield (OK, it's missing a center stone in this ex., but, come on, it's sooo close- and they're ancient, way before the more sophisticated added-center pattern developed):

So now that I've conclusively established with incontrovertible evidence that the Cadash 5-stone symbol is authentically and exclusively dwarven- you know, without any room for doubt at all whatsoever- I began wondering at what it could mean or represent. Aeducan's heraldry is just a bearded dwarf head, symbolizing... um, dwarfhood... at its finest... I guess... or bearddom. The Legion of the Dead heraldry is another dwarf head, just skeletal, likely alluding to their having already had their own funeral as part of joining the Legion. Even Harrowmont has a symbol... a tezpadam... which represents... um, a lot of annoying chirpy things biting ineffectually in a large pack. So what could the Cadash 5-stone heraldry represent? (No, not a bloody flower, you sun-touched, stone-blind, gangue-licker!)
One idea comes from, I believe, the game Warhammer. Apparently they have a symbol like this of a fist... which... could work for four digits and a thumb...

As you see, the thumb does end up in the center, but the other fingers aren't exactly perfectly aligned around it... It's an idea...
A more DA reference I came across was from some obscure google image that purportedly derives from Descent...

It's an otherwise average artwork of a bearded dwarf, but it's been subdivided into sections that correspond exactly to the four outer stones with one single inner stone. The placement of the subdivisions has the center representing a dwarf's heart, the top being a dwarf's mind, the bottom being a dwarf's body, the left and right as a dwarf's... OK, arms. So Cadash is, like, totally far out, man- philosophical and shyt. It's, like, dig it, Cadash represents the True Dwarf, the Way of the Dwarva, the many manifestations of dwarfdom all emanating from the dwarven heart... or something like that... Though I'm not sure if the art I found is from in-game art or promotional material...
Maybe a better idea that came to me was that the Cadash pattern represents a golem. Looking at Caridin (each type of golem has something similar) you can identify the Cadash pattern in them in two ways:

Either the huge breast sections and large gut around that prominent center stone or the prominent breast sections but with the huge shoulders surrounding that tiny head. And the use of round rather than straight-lined images indicates stone, so... naturally the Cadash herald is of a golem, representing golem strength, determination, power, and being subject to a control rod. See? And you guys were thinking like botanists. Sheesh... Hell, you can even see the Cadash symbol in the head shard of the Guardian!

OK, I'll stop while I'm ahead... I am ahead, aren't I?