It is kind of hard if the wall is finished (sheet rock, painted) but not impossible.

Dowel Rods..
I have did it by using Dowel Rods. To hold a 2" thick shelf you will need to use at least 3/4" dowel rods to support the shelf. Now the hard part. You must drill for the rod dead center of a stud. If the rods supporting the shelf is not inserted into studs the shelf will not stay up. For sheetrock can not support the shelf and the weight placed on it alone.

Pocket screws..
Pocket screws and a Kreg Jig for drilling them will also work. But like Dowels they must be placed on studs and then you have the screw pockets to deal with on the underside of the shelf. They can be an eye sore if the shelves are above eye level. Filling the pockets can be done. But to me even that is an eye sore.

I built floating shelves in my last home.

There are multiple ways of doing them.

Obviously the design has to take into consideration the load you will be placing on them. books vs. a few knick-knacks for example take entirely different engineering.

In my case I made hardwood stringers that attached to the wall and then a hollow core "box" that slid over them and snugged up to the wall. the advantage vs.a dowel type system was that I could level the attachment point before i attached to the wall.

There are commercial products out there, I just built my own. Loved the look. I hate brackets too.

best of luck

Thanks hippy & pprioroh, this is the best website....so many creative people! Both of you have great ideas. I'm going to be putting the dishes & glasses & other breakables on these shelves so I want them to be very very sturdy! The last thing I want is for them to come tumbling down! I'll let you know how it goes after all is said & done.

Thank you again for your feedback.