C - Linked list implementation of Stack, having trouble with pop() function?

My push function works fine, but when I pop the last integer entered into my stack, first the last integer changes to zero then if I pop it again it changes to some garbage integer (this is what is showing when running it in the console). I'm guessing it has to do something in pop() where I am not freeing the node correctly..

#include <stdio.h>
#include <stdlib.h>

typedef struct node{
    int data;
    struct node* next;
}Node;


Node* push(Node* root, int value){

    Node* temp = malloc(sizeof(Node));
    temp->data = value;
    temp->next = NULL;

    if(root == NULL){
        root = temp;
    }
    else{
        temp->next = root;
        root = temp;
    }
    return root;
}


int pop(Node* root){

    if(root == NULL){
        printf("nothing to pop, stack is already empty.\n");
        return -1;
    }

    Node* temp = root;
    root = root->next;
    int returnValue = temp->data;
    free(temp);

    return returnValue;
}

int peek(Node* root){

    if(root == NULL){
        printf("Stack is currently empty.\n");
        return -1;
    }
    return root->data;
}

int isEmpty(Node* root){

    if(root == NULL){
        return 1;
    }
    return 0;
}

void display(Node* root){
    printf("\n");
    printf("List: ");
    while(root != NULL){
        printf("%d ", root->data);
        root = root->next;
    }
    printf("\n\n");
}


int main(){

    Node* root = NULL;

    int data, choice;
    printf("\n\nMenu: (1)Push   (2)Pop   (3)Exit\n\n");

    while(1){
        printf("Enter choice: ");
        scanf("%d", &choice);
        printf("\n");

        if(choice == 1){
            printf("Enter data to push: ");
            scanf("%d", &data);
            root = push(root, data);
            display(root);
        }

        if(choice == 2){
            pop(root);
            display(root);
        }

        if(choice == 3){
            break;
        }
    }

    return 0;
}

Don't know where I'm going wrong!