Moms are complicated and varied creatures. So are their kids. Here is some Mother's Day reading designed for mutual exploration and enjoyment. Ages 3-6

"Where Did My Mother Go?" By Edna Mitchell Preston. Illustrated by Chris Conover. (Four Winds, $7.95).

Little Cat's long search for his lost mother and their sweet reunion gently, but clearly, reaffirms the oft-told message: "Never go away unless you tell me where you are going."

"On Mother's Lap." By Ann Herbert Scott. Drawings by Glo Coalson. (McGraw-Hill, $6.95.)

The problems associated with the birth of a sibling know no cultural bounds. In this book of soft-toned drawings depicting Eskimo life, a mother's tender words assure her son that there is always enough room on mother's lap.

"Mother, Mother, I Want Another." By Maria Polushkin. Illustrated by Diane Dawson. (Scholastic, $1.50.)

Baby Mouse's misconstrued bedtime requests put Mrs. Mouse in a tizzy -- and young readers in giggles over his actual desire for simply another goodnight kiss.

"Just for You." By Mercer Mayer. (Golden Press, 95 cents.)

Only a mother could understand and appreciate the well-intentioned but comically clumsy attempts of this furry little creature to prove his love. Ages 5-8

"The Best Mom In The World." By Judy Delton and Elaine Knox-Wagner. Illustrations by John Faulkner. (Albert Whitman, $5.25.)

When Lee Henry's doting mom becomes a working mom he finds the many adjustments difficult . . . but not impossible. Both mother and child discover a new and rewarding dimension to their loving relationship.

"Mother's Day." By Mary Kay Phelan. Illustrated by Aliki. (Crowell, $6.89.)

Young history buffs can learn how Mother's Day originated, as well as the variety of ways in which it is celebrated in other countries. As usual, Aliki's illustrations capture the spirit of the occasion.

"I Want Mama." By Marjorie Weinman Sharmat. Pictures by Emily Arnold McCully. (Harper and Row. $6.89.)

This lonely, little girl wanted her Mama to hurry home from the hospital SOON. Phone calls and letters helped bridge the physical gap, but nothing was as delicious as her mom's welcome-home hug.

"Of Course A Goat." By Ruth Lercher Bornstein. (Harper and Row, $7.95.)

In this serenely illustrated tale of mountain folk, a mother leads her son along a dialogue of fantasy in response to his question, "Mother, may I have a goat?" Ages 8-12

"Abby Takes Over." By Phillis LaFarge. Illustrated by Glo Coalson. (Lippincott, $7.95.)

When Mama goes on vacation for a week, sixth grader Abby takes over running the house. Though Mama's shoes don't fit, Abby realizes by week's end that they belong on a pedestal -- with her Mom's feet in them.

"Ramona and Her Mother." By Beverly Cleary. (Morrow, $6.75.)

With her Father and Mother both working, Ramona begins to feel misunderstood and unloved. Special mother-daughter talks help Ramona learn more about family relationships . . . and about herself.