This is a ripped graphic that you can use for a poison mushroom from the original Super Mario Bros., now as a regular custom sprite. It can be placed in the level or spawned from a block., previously inserted with PIXI using this sprite:
This is a bit too simple of an edit. It would be nice if you did something to the mushroom's cap, like drawing a skull like in SMAS SMB:LL or using more menacing colors like in Super Mario Party. Since this is directly based off of SMAS SMB3's mushroom, you might as well include a version that uses its original shading at the bottom along with palettes from the game, so users that are making SMAS SMB3 styled hacks can make use of this submission.
The palette you used doesn't match the palette used by the custom sprite you linked. The sprite uses palette F and your file overwrites palette B.
Please don't upsize your screenshots too much.
By the way, Graphics Hacks are SMW Graphics submissions that reskin a great deal of SMW's graphics or provide multiple tilesets or otherwise huge amount of graphics, often consisting of a whole SMW Hack made solely for showcasing these graphics. As such, your submission doesn't qualify as one.