Erigeron aureus

Erigeron aureus is  a lovely little plant, common in these parts from montane through to alpine elevations, and, luckily, very recognizable, as it's the only yellow-flowered Erigeron that occurs in this area (the front range Rockies west of Calgary).  

Here are some examples from the Helen Lake/Cirque Peak area, Banff N.P., at the end of August.  The second photo shows Tonestus lyallii in the background.