For a trust to exist the trustee needs to hold property for the benefit of other persons. Cash is ‘property’ and it can easily be transferred. The reason just $10 is used is that the settlor has to give the money to the trustee and not be reimbursed. The settlor is never able to benefit from the trust, for tax reasons. This means the $10 is essentially a gift from the settlor and you don’t want to push the relationship too far by asking them to settle a larger sum. The reason real property isn’t used as the initial property of the trust is because declaring a trust over land will be a dutiable event, usually, and trigger stamp duty. (note that does isn’t always the case, e.g. bare trustees). Declaring a trust over land will also be a CGT event. Note with Testamentary Discretionary Trusts (TDTs) the deceased person is actually the settlor and the settled sum is whatever they leave to the trust. This doesn’t trigger any stamp duty or CGT because of rollover relief for deceased estates.