What charming "little pieces" do you know?

I entirely agree with you about Lyadov's 'Musical Snuffbox' - it's a beautiful gem.

Many of Percy Grainger's works are, in my opinion, mini masterpieces, such 'Country Gardens', 'Handel in the Strand', 'Mock Morris', 'Molly on the Shore', 'Shepherd's Hey!', 'Train Music', etc. Other charmers that come to mind:

Ives - The Circus Band

Ives - Hallowe'en (how appropriate!)

Ives - Remembrance

Ives - Scherzo: all the Way Round and Back

Ives - Song of Harvest Season

Ives - Yale-Princeton Football Game

Satie - 3 véritables préludes flasques

Shostakovich - Tahiti Trot (Tea for Two)

Satie - Le Piccadilly

Varèse - Tuning Up (OK, maybe not charming, but a fascinating 3 minutes)

There are also some sub-four-minute overtures that I return to time and time again:

Bernstein - Candide

Kabalevsky - Colas Breugnon

Mozart - Bastien and Bastienne

Mozart - The Marriage of Figaro

Salieri - Il talismano

March of the Tin Soldiers, #5 in the Tschaikovsky Album for the Young, op. 39, is all in the treble clef.

The lowest note is A below middle C.