Apple Lock / Abaloc Series by Jane Louise Curry

Miggle Arthur devises a tantalizing treasure hunt to entertain her children and their cousins during a summer visit but to her consternation someone else is also interested in the treasure.

In sixteenth-century Wales, a young girl's red-gold hair and lame foot make her suspect to her neighbors who fear that she is a fairy child and capable of magic.

Callie, Liss and Callie's brother Harry stumble into a mysterious underground chamber on a snow-covered hill near their West Virginia mill town and find themselves thrown back into an ancient time, drawn into a strange, perilous ritual performed by the people they find. How will they get home?

It was after he had found a curious silver medallion in a cave along the Ohio River that Dave began seeing the oddly dressed boy on the way to and from school. At first he envied his long hair and exotic clothes -- until he saw that they were both wearing identical medallions and the boy was in his own double... moreIt was after he had found a curious silver medallion in a cave along the Ohio River that Dave began seeing the oddly dressed boy on the way to and from school. At first he envied his long hair and exotic clothes -- until he saw that they were both wearing identical medallions and the boy was in his own double. Envy turned to alarm, then panic when, accepting the boy's proffered medallion in exchange for his own, Dave changed places with him and was thrust eight hundred years back in time, to a castle in medieval Wales. less

A group of children in a crowded school invent a girl who does not exist and find their prank played back at them in a most unexpected way.

At war with his stepmother, in trouble at school, and desperately unhappy, thirteen-year-old Ray Siler was shipped off to strangers- to his mother's kin, the Clarks- like a parcel nobody wanted. Twillys' Green, the high mountain hollow in southern West Virginia where they lived, was another world from anything Ray had known, and it was different somehow even from the isolated, poverty-stricken hollows nearest it. The family name was Clewarek, not Clark, and that was only the first puzzle... moreAt war with his stepmother, in trouble at school, and desperately unhappy, thirteen-year-old Ray Siler was shipped off to strangers- to his mother's kin, the Clarks- like a parcel nobody wanted. Twillys' Green, the high mountain hollow in southern West Virginia where they lived, was another world from anything Ray had known, and it was different somehow even from the isolated, poverty-stricken hollows nearest it. The family name was Clewarek, not Clark, and that was only the first puzzle. Why did they evade his questions about the oddly-dressed people living in the half lean-to and half cave at the base of the hill behind the house? Why were strangers barred from the hollow? When Ray and his uncle Dream uncovered the great stone snake on the wall of the old coal mine high in the hollow, the mystery deepened. And through a splinter of that carved stone, Ray himself was drawn into a conflict that echoed an ancient tragedy played out over sixteen hundred years before. less

Searching for his missing lucky "dreamstone" and the answers to some mysteries surrounding it, Runner, one of the swiftest Tiddi scouts, ventures into the northern Icelands and the grim mountain fortress of Gzel.