It seems to me that many posts in this thread are completely ignoring the policy regarding the Budget Allowance and the Other category. The donation in question is well-intentioned and generous, but as I read the policy, it is not allowed. As was mentioned by RussellHltn, donations to the Budget category are absolutely not allowed; deposits are allowed to the Budget category only for refunds of advances or payments by other units for their share of a budget expense.
As for the Other category, it is to be used for collecting funds for a specific purpose where the person paying the funds receives the benefit. From the lesson
Understanding and Using the "Other" Category:
Most contributions to the “Other” category are not donations to the Church; rather they are payments for a tangible benefit. For this reason they are not considered charitable contributions and will not be included on the year-end tax-valid statement.
The CHI p. 159 says "Stake or ward budget allowance funds should be used to pay for
all Church activities, programs, and supplies. Members should not pay fees to participate (exceptions may be made for annual camps or enrichment activities as explained on page 160)."
I summarize from p. 160: In the case of the cost of
one annual camp or associated equipment, such expenses are to be paid from:
- The Budget Allowance;
- If that is insufficient, participants may earn part or all of the cost;
- If that is insufficient, approved fund-raising activities may be held.
These fund-raising activities do not consist of soliciting donations. Any funds raised in approved ways may not be used to fund any other activities besides the annual camp. There is no provision for receiving donations (even unsolicited) from anyone for any activities, including Cub Scouts.
So back to the original question: based on the above policy statements, my opinion is that the proper course of action is to return the donation to the donor, since it never should have been received in the first place. This would be done by writing a check from Budget, which unfortunately now will hit the 2009 budget allowance, but that detail can be worked out with the stake.
Questions that can benefit the larger community should be asked in a public forum, not a private message.