Please see 25:3. Silver was one of the components of the Mishkan. Was it used?
Rashi says the silver referred to here was not used. This verse refers to items used in the construction of the Mishkan not the vessels. Ibn Ezra quotes the Gaon who suggests an extra silver table was made to fix things, cut or wash. It would also have been used for the trumpets and basins. However Ibn Ezra dismisses this explanation as unnecessary.
Is Ibn Ezra differing from Rashi?
If the silver wasn’t used then what the point of it?
There definitely was a point in having silver in the mishkan, it was used for the adonim, the bases of the walls of the mishkan. Rashi just says that the collection of silver was in way different that the other materials, because everything else was according to each person’s will to donate. The silver on ther other hand was a set amount that each person had to give. Rashi does however add that there was also an aspect of donating of silver, which was used for the utensils of the mishkan, although it wasn’t for the actual building of the mishkan. (See Sifsei Chachomim on Rashi)
The Ibn Ezra however learns that silver that was mentioned here wasn’t needed for the actual building of the mishkan, because it was collected at a different point, however it was needed, therefore it is mentioned, as not to be left out.