Alina,
can't advise you on a mulch issue, but if variegated plant in a center of the first photo is azalea 'Silver Sword' or 'Arctic Rose' please inspect it carefully for the azalea gall. Almost every plant of those two varieties sold thru Lowe and HD (probably from the same grower) for the last 2 years + 2008 was infected. Not a death sentence for the plant, but you are risking to infect all other azaleas in your garden and possibly in a close neighborhood.

Here is a link that might be useful: Leaf gall

Wow George, you scared me! I bought a couple of 'Silver Sword' last year at Home Depot. I also bought a couple of variegated Azaleas at Girard Nursery and one (forgot the name, "Susan something") at the local nursery. I did not notice anything wrong with them, but I did not inspect them closely. They bloomed beautifully this spring. I will inspect them tomorrow. Hopefully, they are OK...
Thanks for the warning!

All Girard's hybrids are highly succeptible to AG.
Silver Sword is a great azalea and and i wouldn't be living without it, but check them all and use fungicide as a preventative measure.

I also bought the brown mulch from Lowes. I added it to my raised bed and noticed it was loaded with tiny white specs. Did you see this with your mulch?? Also, was it the 'brown' mulch you purchased?? My mulch apppears to be somewhere in between both of your in terms of color.
barb

Hi Barb, yes, it has white specs, but it is not colored mulch. Just a "hardwood" one. The "old" mulch has these specs as well. The plants on the bed seem to do OK. The grass has yellowed a little more. I feel better now because it does not seem to affect the health of the plants. I hope it will not act like a slow poison... I have a tree Peony, a 'Silver Flame' Pieris, Hellebores on this bed... I would hate to loose them.
George, my variegated Azaleas look clean to me. The one I bought at the local nursery is 'Christi Lyn'. I have no idea why I thought it is 'Susan...' :-)

Wet mulch turns dark. Bagged mulch will retain heat and moisture will build up inside the bag. Let it dry out for a while and if it's the same kind it will lighten up. If not, then what I would do is sprinkle some of the darker mulch on top of your lighter mulched beds and blend the "dividing line" so the color difference isn't as noticeable. Not sure why your grass turned yellow unless it was putting off just enough heat to burn the grass.