Anthology book with story about robotic bombers

The first short story you described is "Flying Dutchman" by Ward Moore:

It flew toward the city which had long since become finely pulverized rubble. It flew toward the outlying rings of antiaircraft batteries and the few serviceable guns left which would spot it on their radarscreens and automatically aim and fire, attempting to bring it to the fate of all its counterparts. The Flying Dutchman flew toward the country of the enemy, a defeated country whose armies had been annihilated and whose people had perished. It flew so high that far below its outstretched wings and steady motors the bulge of the earth made a great curving line, the earth, that dead planet, upon which no living thing had been for a long, long time.

Here are the covers of the collections it has appeared in. From your description, I think you probably read it in the anthology Science Fiction Stories edited by Tom Boardman, Jr.

Here are the identifications of the other three stories you described; they are all in the same Science Fiction Stories anthology.

1. Hypnotic carving: "The Hypnoglyph" by "John Anthony", pseudonym of John Anthony Ciardi.

Maddick flushed a moment, then pursed his lips almost imperceptibly and shrugged. "Well, what's it for?" he said. He held the thing in front of him and watched his fingers stroke it.

Jaris chuckled again. "It's for exactly what you're doing. The thing is irresistible. Once you've picked it up, your thumb just automatically strokes that little hollow, and it just automatically hates to stop stroking."

2. Wandering robots: "Who Can Replace a Man?" by Brian W. Aldiss.

By early light, the dell looked desolate and cold. From the caves on the far slope, only one man had so far emerged. He was an abject figure. He was small and wizened, with ribs sticking out like a skeleton's. He was practically naked, and shivering. As the big machines bore slowly down on him, the man was standing with his back to them, crouching beside the stream.

When he swung suddenly to face them as they loomed over him, they saw that his countenance was ravaged by starvation.

"Get me food," he croaked.

"Yes, Master," said the machines. "Immediately!"

3. Microscopic aliens: "Pictures Don't Lie" by Katherine MacLean, which you can read at the Internet Archive:

Nathan laughed again harshly, reaching for the mike. "Get them out? There isn't a lake or river within hundreds of miles from here!"

A shiver of unreality went down the Times' spine. Automatically and inanely, he found himself delving in his pockets for a cigarette while he tried to grasp what had happened. "Where are they, then? Why can't we see their spaceship?"

Nathan switched the microphone on in a gesture that showed the bitterness of his disappointment.

"We'll need a magnifying glass for that."