keep in mind mushroom dose-response is NON LINEAR. that means, 3.5g (1/8th) is not twice as much as 1.75 (1/16th), but its exponentially more. 4g is a much higher dose than 3.5g. Once youre up in the 5g range, youre headed for some really intense action. Dont be foolish and think that 7g (1/4th) is double the strength of 3.5g. 7g of shrooms is getting close to superhero strength!
So with that, yes 1g will produce a trip. even .75 will give you some action. You wont be sober. 1.75g is a full on trip imo, albeit without visuals or much of a chance of ego loss. 1.0g will send you out of sobriety, but dont expect anything nearly as interesting as your 4g dose.
As mentioned above, the size of the pile isnt as important as its weight. Assuming the mushrooms are dried, its difficult to judge their density while just being looked at. Weigh them so you know what youre dosing yourself with (All above weights are assuming mushrooms are dried as well - fresh or 'wet' mushrooms require much higher doses and usually result in less accurate assessments).
Be safe!